The ancient philosopher  Aristotle  wrote in The History of Animals VII, part 3 (350 B.C.E) that to avoid conception women must prevent the "womb" from coming in contact with the male sperm by rubbing it with cedar oil, lead ointment or incense, mixed with olive oil. The lead ointment was highly toxic, but the oil was proven to decrease sperm mobility by  Marie Stopes  in the 1930s. Around 300 AD saw the introduction of the  contraceptive sponge  which was inserted into the vagina, so as to prevent conception by absorbing the semen. An Indian prevention recipe from the 8th Century has survived throughout time. The cervical opening was brushed with a mixture of honey and ghee and is then rubbed or mixed with oil rock salt and used to physically block semen. The sticky honey likely reduced sperm motility, and rock salt is now regarded as a spermicide. The works of Iranian author Ibn Sina (980-1037), also known as  Avicenna , has shown to have had 20 different contraceptives in his medical encyclopedia.


While physical methods of contraception were likely present due to their presence and referencing in historical texts, there are also some purposeful behaviors thought to be utilized in preventing unwanted pregnancy. These methods could have been used either out of personal preference, or with heavy influence from religion. Likely the most common used and easiest to hide from the church at the time was coitus interruptus.


Coitus interruptus  is an example of a contraceptive behavior utilized in Medieval times. This is the case with onanism, which is clearly distinguished from masturbation. In the biblical telling, Onan was unwilling to procreate with Tamar, so he withdrew before climax and “spilled his seed on the ground”. [ 8 ]  Masturbation is seen as a form of self arousal, while onanism was viewed as a form of contraception. U.S. judge  John T. Noonan  has written extensively on this topic and believed that the first, certain dated reference to onanism appeared in the ninth century. [ 9 ]  At the beginning, practices of  coitus interruptus  has been linked to circles of prostitution and illicit love affairs within the Middle Ages. [ 10 ]  From there, it took the decisive step towards widespread practice and began entering into conventional sexual relationships, such as marriage. The trigger of this development – assuming other mental and moral conditions – was provided by economic hardship. [ 11 ]  Population control was not a brand new topic during the time. "If too many children are being born," stated the ancient Greek philosopher Plato, writing of the ideal city, "there are measures to check propagation." [ 12 ]  Medieval demography has been linked to the church's teaching on birth control. Demographic statistics of the early fifteenth century provide evidence that married couples were limiting the number of offspring they had, likely with such methods as  coitus interruptus . This was particularly true with poor couples and in periods of economic hardship. [ 13 ]  The purposeful prevention of pregnancy is brought into juxtaposition with the church's moralist denunciation of contraception.


The  Catholic Church  sees procreation as an essential end of marriage, and entering into an intentionally childless marriage nullifies the sacrament of matrimony. [ 14 ]  This goes back as far as  Pope Gregory IX  and his  decretal  dating from between 1227 and 1234 which declared that marriages contracted by parties intending to avoid having offspring were  ipso facto  null. [ 15 ]


Natural Cycles  is the company behind the Natural Cycles birth control app. The app was the first to be certified as a contraceptive in the  European Union  and in August 2018 the  Food and Drug Administration  approved U.S. marketing for the contraceptive app as a Class II medical device. [ 1 ]  It remains the only digital form of birth control on the market in the United States and has also received regulatory clearances from Canada ( Health Canada ), Australia ( TGA ), Singapore ( HSA ), and South Korea ( MFDS ) [ 2 ] .


The Stockholm-based company, which was co-founded by particle physicists  Dr. Elina Berglund Scherwitzl  and Dr. Raoul Scherwitzl, has received $100 million in funding.


Berglund was a physicist partly based at CERN, collaborating with the team who discovered the  Higgs boson , before co-founding the company with her husband Scherwitzl. Because the couple was in search of an alternative natural contraceptive themselves, Berglund used data analysis to develop an algorithm designed to pinpoint her ovulation.


The couple then decided to create an app with the underlying algorithm, Natural Cycles. Following several medical trials, the app became the first tech-based device to be certified for use as contraception in the  European Union  in February 2017 by the European inspection and certification organisation  TÜV SÜD . [ 3 ]  In November 2017 Natural Cycles received a $30M investment in series B round led by  EQT Ventures  fund, with participation from existing investors Sunstone,  E-ventures  and Bonnier Growth Media (the  VC  arm of privately held Swedish media group, the  Bonnier Group ). [ 4 ]


While the app is currently only certified in the European Union, where its users are concentrated in the  United Kingdom  and the  Scandinavian  countries, it is available worldwide. Natural Cycles offers a subscription product, which had over 800,000 users across 160 countries as of June 2018. 75 percent use the app as a contraceptive, and the rest use it to try to become pregnant. [ 5 ]


The app works by having users take their temperature each morning immediately after waking and logging it into the app. This is done with a  basal thermometer . The apps  algorithm  calculation is based on the observation that post-ovulation,  progesterone  warms the female body by up to 0.45 °C. [ 6 ]  Natural Cycles algorithm then determines, based on the temperature, whether the user is fertile or not. A red day means fertile (which is when one should abstain or use a  condom ); a green day means not fertile. [ 7 ]  For the app to remain effective, women need to follow the app's instructions correctly, and it does not protect its users from  sexually transmitted diseases . [ 3 ]


In 2019, the company completed a pilot program in Sweden that tested a feature to help women trying to get pregnant determine if they should seek fertility help. [ 8 ]  A new mode also became available in 2019 that helps users monitor pregnancy. [ 8 ]


Studies carried out by the app's creators have found it to be as effective in preventing pregnancies as the contraceptive pill for  typical use  (for perfect use, Natural Cycles effectiveness was lower than the contraceptive pill's). [ 9 ] [ 10 ]  These studies, however, only consider women who were paying members and were within the age range 20-35. [ 11 ] [ 12 ]


In 2018,  Södersjukhuset , a hospital in Stockholm, Sweden, filed a complaint with the Medical Products Agency of Sweden after 37 women who had been using Natural Cycles as their primary method of contraception sought an abortion at the hospital after becoming pregnant unintentionally. [ 13 ]  Natural Cycles responded by saying the number of pregnancies was within the reported effectiveness rates. [ 14 ] [ 15 ]  In the UK, the app came under investigation by the  Advertising Standards Authority  over supposedly misleading claims in its marketing; the complaint was upheld by the ASA in August 2018, concluding that the app misled consumers regarding being "highly accurate" and a "clinically tested alternative to birth control". [ 16 ]  A number of users and healthcare professionals have expressed concerns over the efficacy of the app. [ 17 ]


In August 2018, Lauren Streicher, professor of clinical obstetrics at  Northwestern University 's  Feinberg School of Medicine  expressed concerns over the  Food and Drug Administration's  approval of the app. Streicher has claimed that the app is "problematic" as it relies on users' self-reported temperatures which must be taken as soon as they wake up each morning in order to be accurate. In an interview with  Vox , Streicher claimed "The minute you rely on action, the efficacy goes down." [ 18 ]


Natural Cycles has also been criticised for its marketing strategy of paying social media influencers to promote the app. In July 2018 researchers at the  London School of Hygiene and Tropical Medicine  published a study which claimed "Natural Cycles' marketing materials ought to be entirely transparent, more clear than they currently are about the limitations of their app and pregnancy risks". [ 11 ] [ 18 ]


Natural fertility  is the fertility that exists without birth control or other medical interventions. The control is the number of children birthed to the parents and is modified as the number of children reaches the maximum. Natural fertility tends to decrease as a society modernizes. Women in a pre-modernized society typically have given birth to a large number of children by the time they are 50 years old, while women in post-modernized society  only bear a small number by the same age. [ 1 ]  However, during modernization natural fertility rises, before family planning is practiced. [ 2 ]


Historical populations have traditionally honored the idea of natural fertility by displaying fertility symbols. [ 3 ]


Natural fertility is a concept developed by the  French  historical  demographer   Louis Henry  to refer to the level of fertility that would prevail in a population that makes no conscious effort to limit, regulate, or control  fertility , so that fertility depends only on physiological factors affecting  fecundity . In contrast, populations that practice  birth control  will have lower fertility levels as a result of delaying first births (a lengthened interval between  menarche  and first  pregnancy ), extended intervals between births, or stopping child-bearing at a certain age. Such control does not assume the use of artificial means of fertility regulation or modern contraceptive methods but can result from the use of traditional means of  contraception  or pregnancy prevention (e.g.,  coitus interruptus ). Many social norms or practices affect fertility regulation including  celibacy , the age at marriage and the timing and frequency of  sexual intercourse , including periods of prescribed  sexual abstinence . Breastfeeding has also been used to space births in areas without birth control. [ 4 ]   Ansley Coale  and other demographers have developed several methods for measuring the extent of such fertility control, in which the idea of a natural level of fertility is an essential component. [ 5 ]


When women have access to birth control, they can better plan their pregnancies. This leads to better health outcomes and enhances their lives and those of their families. Birth control has dramatically improved the ability of all women to participate actively and with dignity in economies across the world. [ 6 ]  Birth control allows many women to delay childbearing until they believe they are emotionally, physically and financially ready to be a parent. Children who are born in an unplanned pregnancy tend to occur outside relationships. Birth Control has been the main tool to prevent unplanned births, and with greater access to birth control unplanned pregnancies have declined. [ 7 ]


Proximate determinants describe variables that affect a female's fertility. There are seven proximate determinants of natural fertility, four of which affect the inter-birth interval: [ 8 ]


Factors like the age at which a woman marries and the inter-birth interval are influenced by social factors like education, religion, and wealth. Educated women tend to delay childbirth and have fewer offspring. [ 9 ]  In sub-Saharan Africa where gender disparities in education are more prevalent, fertility rates are the highest in the world. [ 10 ]  Globally, 58 million girls do not attend primary school. Half of those girls live in sub-Saharan Africa; this disparity only widens as the level of education increases. [ 11 ]  Prevalence of child marriage is an attributing factor to the fertility rates in India as women ages 20–24 reported that they had never used contraception prior to giving birth or within their first year of marriage. Child marriage in India primarily occurs in girls living in poor socioeconomic conditions. Furthermore, women married as minors in  South Asia , where half of child marriages occur, reveal having high numbers of unwanted pregnancies than their counterparts that married as adults. [ 12 ]


Common reasons communities or individuals will practice natural fertility include concerns about developing medical conditions (including future infertility), pre-existing health conditions (including  PCOS ), cost of birth control, religious prohibition, lack of availability of birth control, and lack of information about birth control methods. Location also tends to be a factor in regards to the availability of both contraceptives and education on sexual practice. For example, less developed areas, including, but not limited to those extending throughout inland  Africa  lack access to the drugs necessary to control fertility or informative lessons describing their correct usage. [ 14 ]


The number of children born to one woman can vary dependent on her window from menarche to menopause. The average window of fertility is from 13.53 to 49.24. [ 15 ]  Taking into consideration lactational amenorrhea and the period between conception and birth, the average woman is capable of experiencing around 20 births. However, if the duration of lactation is cut short due to use of a formula substitute or the woman has  multiple births , the number of offspring could exceed 20.


Natural fertility is not only influenced by women and their conscious or unconscious decisions, but also their male counterparts. Even if a woman does not take contraceptives, lacks knowledge of family planning, or does not practice regulated fertility, she might not be able to conceive. Over the past half century, there has been an increase in scientific data supporting the decline in male  sperm count . [ 16 ]  The decrease is attributed to various  environmental toxins  that are accumulating as the planet continues to industrialize. If sperm count remains above 60 million per ejaculate, fertility remains normal. But sperm counts are continuing to drop. At such low levels, the sperm often are incapable of successfully  fertilizing  the egg. A decline in male fertility often means a decline in natural fertility, as fertility is carried by both sexes.


Ansley J. Coale  developed a theory to predict when a population's fertility would begin to decline. His theory focused on three specific aspects. First, a couple must make conscious choice to control their fertility. This is closely related to secularization as some religions prohibit means of contraception. Second, there must be a benefit to controlling fertility that results in the desire for a smaller family. For example, as more regions move away from agriculture children are no longer needed to help with labor and fertility rates and family size tend to decrease. Third, the couple must be able to control fertility. This means that access to contraceptives or other means of limiting fertility must be available. [ 17 ]


Coale's preconditions for fertility decline is interrelated to the  Demographic Transition , a theory of the transition of societies from an agricultural to an industrial system. A more modernized society has lower mortality and fertility rates while a less modernized society tends to have higher mortality and fertility rates. [ 18 ]   Developing countries  in the early stages of the demographic transition are characterized by high fertility and mortality rates which can be attributed to the lack of medical interventions like  birth control  and modern technology. [ 19 ]  Communicable diseases and contaminated resources like water and consequently food, plague developing countries. As a consequence, people of all ages die in masses. Coale's theory favored a fertility decline as a smaller population would allow for a more beneficial spread of resources and keep the number of ill individuals concentrated to a smaller group. In addition, Coale viewed the development of Europe's infrastructure during the  Industrial Revolution  as a mark in its transition in the demographic transition. Mortality and fertility rates declined with their improved standard of living. [ 18 ]  Infant mortality rates are indicative of fertility rates as couples decide to have a lot children knowing that a number of them will die so that even after those children die, they have sufficient kids to aid in agricultural work. Conversely, developed countries in the later stages of the demographic transition experience lower fertility and mortality rates due to the accessibility of contraception, the pursuit of higher education in women, and marriage at a later age. [ 19 ]


Coale's theory can be observed in  sub-Saharan Africa  as countries residing within this region have fertility levels that are declining at a much slower rate than before and have one of the highest projected population growths compared to other areas of the world. [ 10 ]  Individuals inhabiting sub-Saharan Africa have slowly rejected Coale's second precondition for fertility decline which, as stated before, is willingness. They are resistant and unwilling to accept the integration of modern forms of contraception. This can be attributed to the influence of religion and the values it imposes on culture even in individuals who don't practice any religion. [ 20 ]  To add on, the society they live in encourages young marriages and values large families. Despite the discrepancy between preferred child bearing and natural fertility, women in Africa have reported they don't use any form of contraception to prevent pregnancies. [ 21 ]  All of these factors have contributed to the slowing down of fertility decline in Africa. As of now, an uninterrupted African  baby boom  is to be expected. [ 22 ]


Opill  is a  birth control pill  formulated from  norgestrel , which works to thicken the cervical mucus and prevent pregnancy. [ 1 ]  Opill is manufactured by  HRA Pharma  and is the first ever over-the-counter contraceptive to be sold in the United States. [ 2 ]  Opill is solely intended to be used for pregnancy prevention. It is not intended for use in emergency situations or for prevention of  sexually transmitted diseases or infections . [ 3 ]  Opill is marketed through social media and its partnership with the  Women's National Basketball Association (WNBA) . [ 4 ]


Opill was acquired by  Perrigo  during their acquisition of HRA Pharma, along with  ellaOne  and  Hana , other over-the-counter emergency contraceptives. [ 5 ]


Opill was approved by the  Food and Drug Administration (FDA)  for over-the-counter use on July 13, 2023. [ 2 ]  This approval was given to its manufacturer a year after their initial application for the prescription to over-the-counter switch. [ 6 ]  This came a year after the overturning of  Roe v. Wade , which heavily restricted or criminalized abortion in 24 states. [ 7 ]


Opill began sale at major retailers in the U.S., including CVS, Target, Walgreens, and Walmart in March 2024. It is also available online from the Opill website and Amazon. [ 8 ]


Opill is a progestin-only daily birth control pill, also known as a “ mini pill ,” available over-the-counter without the need for health insurance. [ 1 ] [ 3 ]  It has no age restrictions and is safe to use as long as  menstruation  has started. The pill should be taken orally at the same time each day for optimal effectiveness; it is 98% effective when taken correctly and 91% effective with typical use. [ 1 ] [ 9 ]  Opill begins working 48 hours after the first dose. [ 10 ]


Opill is intended solely as a contraceptive and does not function as  emergency contraception , provide protection against  sexually transmitted infections  (STIs), or act as an  abortion medication . [ 3 ]  Common side effects include irregular vaginal bleeding, headaches, dizziness, nausea, increased appetite, abdominal pain, bloating, and cramping. [ 2 ]


Opill can be purchased online through the company’s website or found in the family planning aisles of most drug stores, convenience stores, and grocery stores. Opill's presence in the family planning aisle could help reduce the U.S.' unplanned pregnancy rate of 41.6% as of 2019. [ 11 ] [ 12 ]


When it comes to testing and labeling, Opill used several surveys to make sure that consumers could follow the instructions on dosing and understand the package labels. [ 13 ]  This is an important step to the brand since consumers take the medication without doctor supervision. The colors of the packaging are also designed with the idea of avoiding gender-based stereotypes. They use a variety of colors, mainly teal with accents of blue, purple, and pink. [ 13 ]  This variety of bright colors not only sets Opill apart, but it helps consumers gain brand recognition.


Opill also works with  Snapchat  to spread awareness to  Generation Z . The results of the campaign report an increase in brand awareness by 24%. [ 14 ]  According to Leila Bahbah, US Women's Health Brand Lead and Associate Director of Opill, Snapchat was a key player in reaching Gen Z audiences. [ 14 ]


In April 2024,  Perrigo  partnered with The  Women's National Basketball Association  to work together to build confidence and health equity. Colie Edison, Chief Growth Officer for the WNBA, said that the WNBA is dedicated to addressing issues important to the organization such as reproductive health. [ 4 ]  This is why this multi-year partnership aligns with both Perrigo and WNBA's core beliefs. They are working to increase accessibility and reach students on college campuses across the country. [ 4 ]


Norgestrel  is a progestin used in birth control pills, such as the Opill, which contains a synthetic version of the naturally occurring hormone  progesterone . [ 1 ] [ 15 ]  The Opill contains 0.075mg of the active ingredient norgestrel, along with inactive ingredients including  cellulose ,  FD&C Yellow 5 ,  lactose ,  magnesium stearate , and polacrilin potassium. [ 16 ]


The Opill primarily works by thickening the  cervical mucus , making it harder for sperm to reach the egg. [ 10 ] [ 17 ]  It can also prevent the release of eggs from the ovaries during some menstrual cycles and thins the  uterine lining , creating a less hospitable environment for a fertilized egg to implant. [ 10 ] [ 16 ]


Progesterone plays a crucial role in preventing pregnancy by stopping  ovulation . It works by inhibiting the development of ovarian follicles, preventing the release of an egg. This process is regulated by negative feedback on the hypothalamus, reducing the secretion of hormones like  follicle-stimulating hormone  (FSH) and  luteinizing hormone  (LH). Without follicle development,  estradiol  levels remain low and the LH surge necessary for ovulation is blocked, effectively preventing ovulation. [ 16 ] [ 18 ]


Opill is currently available in all states in the U.S. after it was approved by the FDA on July 13, 2023. The active ingredient in Opill, Norgestrel, was legalized for prescription use in 1973. However, it was discontinued by the manufacturer in 2005. [ 1 ]  Opill is available in major retailers like Walmart, Target, CVS, and Walgreens. In stores, a one month supply is sold for $19.99, and a three month supply is sold for 49.99. [ 19 ]  Perrigo also offers a "Cost Assistance Reduction" program for those that are eligible.


Currently, there are no legal restrictions placed on the Opill, however, that could change as it did with the oral abortion pill  Mifepristone . [ 11 ]


World wide, over-the-counter birth control is legal in most of Africa, South America, and Asia. However, in most of Europe it still requires a prescription. [ 20 ]


Fenella Paton  or  Fenella Crombie  (29 January 1901 –  21 October 1949) was a  philanthropist  and pioneer of women. She founded the first birth control clinic in  Aberdeen . [ 1 ] [ 2 ]


Paton was born in  London  to Minna Wason and  John W. Crombie . [ 2 ]


She was born into a political family. Her father was a  Liberal  MP for  Kincardineshire [ 1 ]  and her grandfather was Liberal MP  Eugene Wason . [ 2 ]


Paton married  John David Paton , of  Grandhome , in 1923. [ 2 ]  They resided in Aberdeen and had two sons and four daughters. [ 2 ]


Inspired by  Marie Stopes  work, Paton founded the  Aberdeen Women's Welfare Centre  in 1926. [ 3 ]  It provided advice on  birth control  to local women.


Paton ran the clinic along with volunteers. Initially the team consisted of a family doctor,  Dr Florence Malcolm , and a Nurse,  Mrs Rae . [ 3 ]  Although the clinic was not associated with Marie Stopes' organisation, Paton and Stopes corresponded and Stopes visited the clinic in 1933. [ 3 ] [ 4 ]  After this visit,  Dr Kathleen Fraser  was appointed. [ 3 ]


The clinic was funded by Paton, her mother, and friends. [ 2 ]  In 1935,  Aberdeen City Council  started to partially fund the centre. The clinic was funded by Paton until 1948, when it was transferred to the  National Health Service . [ 1 ]


Paton was a member of several charities and organisations in Aberdeen, including the  YWCA . [ 2 ]


She was praised for her involvement in  St Katherine's Community Club , which helped girls from working-class backgrounds by organising social and educational activities. [ 2 ]


The  Pearl Index , also called the  Pearl rate , is the most common technique used in  clinical trials  for reporting the effectiveness of a  birth control  method. It is a very approximate measure of the number of unintended pregnancies in 100 woman-years of exposure that is simple to calculate, but has a number of methodological deficiencies.


The index was introduced by  Raymond Pearl  in 1934. [ 1 ]   It has remained popular for over eighty years, in large part because of the simplicity of the calculation.


Several kinds of information are needed to calculate a Pearl Index for a particular study:


There are two calculation methods for determining the Pearl Index:


The Pearl Index is sometimes used as a statistical estimation of the number of  unintended pregnancies  in 100 woman-years of exposure (e.g. 100 women over one year of use, or 10 women over 10 years). It is also sometimes used to compare birth control methods, a lower Pearl index representing a lower chance of getting unintentionally pregnant. [ 2 ]


Usually two Pearl Indexes are published from studies of birth control methods: [ 3 ]


Like all measures of birth control effectiveness, the Pearl Index is a calculation based on the observations of a given sample population. Thus, studies of different populations using the same contraceptive will yield different values for the index.  The culture and demographics of the population being studied, and the instruction technique used to teach the method, have significant effects on its failure rate. [ 4 ] [ 5 ]


The Pearl Index has unique shortcomings, however.  It assumes a constant failure rate over time.  That is an incorrect assumption for two reasons: first, the most fertile couples will get pregnant first.  Couples remaining later in the study are, on average, of lower fertility.  Second, most birth control methods have better effectiveness in more experienced users.  The longer a couple is in the study, the better they are at using the method.  So the longer the study length, the lower the Pearl Index will be – and comparisons of Pearl Indexes from studies of different lengths cannot be accurate. [ 6 ]


The Pearl Index also provides no information on factors other than accidental pregnancy which may influence effectiveness calculations, such as:


A common misperception is that the highest possible Pearl Index is 100 – i.e. 100% of women in the study conceive in the first year.  However, if all the women in the study conceived in the first month, the study would yield a Pearl Index of 1200 or 1300.  The Pearl Index is only accurate as a statistical estimation of per-year risk of pregnancy if the pregnancy rate in the study was very low.


In 1966, two birth control statisticians advocated abandonment of the Pearl Index: [ 7 ] [ 8 ]


[The Pearl Index] does not serve as an estimator of any quantity of interest, and comparisons between groups may be impossible to interpret... The superiority of life table methods or other estimators that do not assume a constant hazard rate seems clear. [ 9 ]


POPLINE  (or Population Information Online) [ 1 ]  was a reproductive health  database , containing citations with abstracts to scientific articles, reports, books, and unpublished reports in the field of  population ,  family planning , and  reproductive health  issues.  POPLINE was maintained by the K4Health Project [ 2 ]  at the  Johns Hopkins Bloomberg School of Public Health / Center for Communication Programs , and it was funded by the  United States Agency for International Development  (USAID).


The original database consisted of citations from Popinform, a database maintained from 1973 to 1978 by the Population Information Program (PIP) at  George Washington University . In 1978, the database, along with Population Information Program, moved to the  Johns Hopkins University . Between 1980 and 2001, renamed POPLINE, the database became part of the  United States National Library of Medicine 's (NLM) Medical Literature Analysis and Retrieval System (MEDLARS) along with  MEDLINE  and other NLM databases.


Since 2001, POPLINE had been maintained by the Knowledge for Health (K4Health) Project, formerly PIP then INFO, based at the  Johns Hopkins Bloomberg School of Public Health /Center for Communication Programs. Access to POPLINE was available free of charge at its website. Other organizations contributed to POPLINE throughout its history, such as the  Center for Population and Family Health  (CPFH) Library/Information Program at  Columbia University , Population Index at  Princeton University , and the Carolina Population Center (CPC) at the  University of North Carolina .


On September 1, 2019, POPLINE was officially retired along with the rest of the Knowledge for Health (K4Health) Project which closed a few days later. [ 3 ]


POPLINE provided more than 370,000 records citing worldwide literature in the area of reproductive health. The majority of items were published from 1970 to the present, but there were selected citations dating back to 1827.  The database added 12 thousand records annually and was updated weekly.


The database consisted of  bibliographic citations  and  abstracts  to a variety of materials including journal articles, monographs, technical reports, and unpublished literature.


Subjects covered internationally included family planning methods and programs,  fertility , and population law and policy. Additional subjects covered in reference to developing countries include  adolescent  reproductive health,  demography ,  environmental health , gender and health,  health communication ,  sexually transmitted infections , maternal and child health, population and environment, and  women in development .


POPLINE had both basic and advanced searches and offered customized searches provided on request to persons or institutions in developing countries. Full-text copies for most of the documents cited in POPLINE could be requested from users in low-income countries free of charge via mail or sent by email. In addition to free text searching, the database could be searched by keywords from the POPLINE Thesaurus, a controlled vocabulary of 2,400+ terms used to index documents in the database.


In 2008, the  New York Times  reported that  Johns Hopkins University  had instructed the POPLINE search engine to ignore the search term "abortion", as it ignores search terms such as "a" and "the", in February 2008 in response to pressure from the  United States Agency for International Development . Making the term a  stop word  removed the ability of users to search for this common term for a reproductive health issue.


After learning of the restriction on finding abortion-related articles, the dean of the  Johns Hopkins Bloomberg School of Public Health , Michael J. Klag, lifted the restriction. [ 4 ] [ 5 ]


Population control   is the practice of artificially maintaining the size of any  population . It simply refers to the act of limiting the size of an animal population so that it remains manageable, as opposed to the act of protecting a  species  from excessive rates of  extinction , which is referred to as  conservation biology . [ 1 ] [ 2 ] [ 3 ]


While many abiotic and biotic factors influence population control, humans are notably influential against animal populations. Whether humans need to hunt animals for food, exterminate a  pest , or reduce competition for resources, managing populations involves providing nourishment, or  neutering  to prevent reproduction, culling individuals or the use of pesticides. Population control plays an important role in wildlife populations. Based on the species being dealt with, there are numerous ways populations of the wild are controlled.  Wildlife contraception  is the act of preventing reproduction in the wild, which subsequently decreases populations. An example of this includes the maintenance of deer populations with the use of vaccines. [ 4 ] [ 5 ]  Other methods to maintain populations include lethal trapping, live trapping, egg/roost site manipulation, live-ammunition shooting, and chemical euthanization. Lethal trapping, egg/roost site manipulation, live-ammunition shooting, and chemical euthanization are methods used to eliminate animal populations and prevent reproduction, whereas live trapping captures species to remove them from a specific area. [ 6 ]


Population control can be influenced by a variety of factors. Humans can greatly influence the size of animal populations they directly interact with. It is, for example, relatively common (and sometimes even a legal requirement) to  spay  or  neuter  dogs. Spaying – removing the ovaries and uterus of a female animal – medical term =  ovariohysterectomy . Neutering - removing the testes of a male animal – medical term =  orchiectomy . Various humans activities (e.g. hunting, farming, fishing, industrialization, and urbanization) all impact various animal populations.


Population control may involve  culling ,  translocation , or manipulation of the reproductive capability. The growth of a population may be limited by environmental factors such as food supply or  predation . The main biotic factors that affect population growth include:


Important  abiotic  factors affecting population growth include:


Direct human impacts are not the only ways humans can control animal populations. Often times, humans are indirectly controlling animal populations, in other words, the humans are not aware that their actions are controlling animal populations. For example, new infrastructure and roads can lead to animals being displaced from their natural habitat. Their new habitats that they are forced to move to may not provide the same necessities to them that they require for survival. This will result in a decreasing population as a result of human actions.


Animal euthanasia  is often used as a final resort to controlling animal populations. In  Tangipahoa Parish, Louisiana , the parish performed mass euthanasia on the entire  animal shelter  population, including 54 cats and 118 dogs that were put to death due to a widespread disease outbreak that spread among the animals. [ 9 ]


Neutering  is another option available to control animal populations. The annual  Spay Day USA  event was established by the  Doris Day Animal League  to promote the neutering of pets, especially those in  animal shelters , so that the population remains controllable. [ 10 ]


Wildlife contraception  is used to regulate populations of animals in the wild and halt reproduction. For example, vaccines are currently being used in deer populations. GonaCon, which was developed by the US Department of Agriculture, encourages the production of antibodies in the sex drive hormones. [ 4 ]  Specifically, it is said to remove the oestrous cycles from the females, which initially attracts the males; without the oestrous cycles, males are not interested in mating. [ 4 ]  Another type of vaccine that is being used in deer is called porcine zona pellucida (PZP). [ 5 ]  PZP works by blocking sperm with antibodies on the deer's egg surface. [ 5 ]


When preventing reproduction fails to control populations, methods such as lethal trapping, live trapping, egg/roost site manipulation, live-ammunition shooting, and chemical euthanization are used to maintain populations.


Lethal trapping  is a method used to kill animals. This type of method is usually monitored in order to ensure no ethical or public concerns arise. While this tactic is most commonly used on small animals, populations of larger animals such as beavers and foxes are also controlled with this type of method. [ 6 ]


Live trapping  is a method used to capture a variety of animals. From small animals to large animals, this type of population control method uses barrel traps, restraining snares, and leg-hold devices. Just like the lethal trapping method, this tactic also needs to be regularly monitored to ensure no ethical concerns arise, as well as reduce animal distress. Specifically, this type of population control method is popular with capturing birds. [ 6 ]


Egg/roost site manipulation  is used on birds to prevent them from nesting in prohibited areas. Water spray is popular in urban and agricultural areas as it uses sprinklers to emit surfactants. The surfactants then control bird populations by killing and preventing future birds from nesting. [ 6 ]


Live-ammunition shooting  uses firearms to eliminate animals such as birds and bears. Because this type of population control method is restricted in many parts of the world, it is only to be used when other control methods have failed. [ 6 ]


Chemical euthanization  refers to the use of chemicals to cause an easy or painless death and is divided into three categories: acute toxins, anticoagulants and decalcifiers, and fumigants. [ 6 ] [ 11 ]  Acute toxins only require a single dose to kill animals, whereas anticoagulants and decalcifiers require numerous doses over time. Fumigants are used to suffocate animals underground. [ 6 ]  While this type of population control method poses ethical concerns, the World Society for the Protection of Animals (WSPA) believes it is necessary when human health or the safety of other animals are at risk. To ensure this control method is humane, WSPA states that it must be painless, achieve rapid unconsciousness followed by death, minimize animal fear and distress, and be reliable and irreversible. [ 12 ]


Population control also plays a significant role in managing and controlling invasive species so that they are eliminated before becoming abundant and causing any ecological harm. [ 13 ]


Several efforts have been made  to control the population of  ticks , which act as  vectors  of a number of diseases and therefore pose a risk to humans. Efforts are also continuously being made to control wildlife populations near airports. Specifically, control measures have been approved for bald eagles and deer. [ 6 ]


The  Population Council  is an international, nonprofit, non-governmental organization. The Council conducts research in  biomedicine ,  social science , and  public health  and helps build research capacities in  developing countries . [ 1 ] [ 2 ]  One-third of its research relates to HIV and AIDS; while its other major program areas are still linked to its early foundation in  reproductive health  and its relation to poverty, youth, and gender. [ 3 ]  For example, the Population Council strives to teach boys that they can be involved in contraceptive methods regardless of stereotypes that limit male responsibility in child bearing. [ 3 ]  The organization held the license for  Norplant  contraceptive implant, and now holds the license for Mirena  intrauterine system . The Population Council also publishes the journal  Population and Development Review , which reports scientific research on the interrelationships between  population  and  socioeconomic development . It also provides a forum for discussion on related issues of public policy and  Studies in Family Planning , which focuses on public health, social science, and biomedical research involving  sexual and reproductive health ,  fertility , and  family planning .


Established in 1952 by  John D. Rockefeller III , with important funding from the  Rockefeller Brothers Fund , the Council is governed by an international board of trustees. After many years of evolving, the 2006 council board includes leaders in many different fields. These include: biomedicine, business, economic development, government, health, international finance, media studies, philanthropy, and social science. [ citation needed ]


Headquartered in New York City, the Population Council has 18 offices in Africa, Asia, and Latin America and does work in more than 60 countries. With an annual budget of around $74 million, it employs nearly 400 people from 33 countries with expertise in a wide array of scientific disciplines. Roughly 55 percent are based outside the United States. [ citation needed ]


John D. Rockefeller III convened distinguished scientists in Williamsburg, Virginia, under the auspices of the National Academy of Sciences, to begin the search for a better understanding of  demographic  trends. Shortly thereafter, in 1952, he established the Population Council as an independent, nonprofit organization. He served as the Council's first president. [ 4 ]  Rockefeller eventually became non-executive chairman of the board, serving until his death in an auto accident in 1978. [ 5 ]


Population Council presidents following Rockefeller are:  Frederick Osborn  (1957–1959),  Frank Notestein  (1959–1968),  Bernard Berelson  (1968–1974), George Zeidenstein (1977–1992),  Margaret Catley-Carlson  (1993–1999), Linda Martin (2000–2004), Peter J. Donaldson (2005–2015),  Julia Bunting  (2015–2023), and Interim co-Presidents Patricia C. Vaughan and James Sailer (2023-2024). [ 6 ] [ 7 ] [ 8 ] [ 9 ] [ 10 ]


The Population Council conducts biomedical research to develop  contraceptives  and social science research to better understand the factors influencing access to and decision-making around contraceptives. [ 11 ]  Its research on reproductive and immunological processes serves, not only as the basis for the development of new contraceptive methods that reach out to both men and women, but also for new hormone therapies and AIDS-prevention products. The council is involved in a "collaboration with industry partner ProMed Pharma to develop innovative new vaginal rings that may make STI prevention more acceptable and effective for women." [ 12 ]


In the 1960s, the Council played a key role in documenting the large numbers of people in poor countries who lacked access to contraceptives and in conducting research to design and evaluate public  family planning  programs. This included bringing IUDs to India. [ 13 ]   At this time, the Council's biomedical researchers worked to develop contraceptive methods, such as the intrauterine device. The council has found that fertility is "most sensitive to changes in the proportions married and prevalence of contraception." A country's ideas around reproduction out of wedlock, its accessibility, and the public's opinion of birth control are instrumental in the region's fertility. [ 14 ]


An array of contraceptives available around the world today were developed by the Population Council, including: the  Copper T Intrauterine device ,  Norplant ,  Jadelle (Norplant II) ,  Mirena , and, in 2018, a one year contraceptive vaginal system called Annovera was approved by the US FDA. [ 15 ]  More than 50 million Copper T IUDs have been distributed in over 70 countries. Norplant was replaced by Jadelle, a two rod implant that provides contraception for five years. [ citation needed ]


The British medical journal  Lancet  said of the Population Council, "Most non-governmental organizations claim to promote change; the Population Council actually has hard evidence of having changed the lives and expectations of hundreds of millions of people." [ 16 ]


The Population Council provides programs all over the world that aim to address the prevention and treatment of the HI virus. These programs help to develop new technologies and distribute them to marginalized populations, and also educate people about HIV through workshops and mentorship services. For example, Empowering Girls and Young Women at High Risk of HIV Infection: A Capacity Strengthening Project is a project with locations in 15 different African countries that reaches girls and young women who have the highest risk of HIV transmission and provides them with resources to prevent the virus. [ 17 ]


The Council is constantly conducting research to find high risk populations and the most cost-effective ways to get them the treatment they lack. The Council partners in a project called Link Up that is based in Bangladesh, Burundi, Ethiopia, Myanmar, and Uganda, which focuses on the population of young people ages 10 to 24 who represent a large proportion of HIV infections. [ 18 ]  The Council's research and involvement in this project helped to implement more effective strategies for improving the sexual and reproductive health of these populations. [ citation needed ]


The Council helps to alleviate the harmful effects of sexual and  gender-based violence  by offering education to both men and women about domestic violence and provide programs to help victims. Programs like "Opening Opportunities" help to develop the social networks of girls who are most at risk of being involved in sexual or gender based violence, and also connects them with mentors to help them stay safe. [ 19 ]


The research that the Population Council conducts, and the publications it releases based on that research, contribute to the data that demographers and health officials require in order to promote public health. For instance, the Population Council was one of the first organizations to document statistics on HIV in Africa. The council also conducted the first study in India to assess the HIV risks that injecting drug users face. [ 20 ]  Their persistent efforts help to provide information about and combat public health disparities. [ citation needed ]


Globally approximately 45% of those who are married and able to have children use  contraception . [ 1 ]  As of 2007,  IUDs  were used by about 17% of women of child bearing age in developing countries and 9% in developed countries or more than 180 million women worldwide. [ 2 ]  Avoiding sex when fertile is used by about 3.6% of women of childbearing age, with usage as high as 20% in areas of South America. [ 3 ]  As of 2005, 12% of couples are using a male form of contraception (either  condoms  or a  vasectomy ) with rates of up to 30% in the developed world. [ 4 ]


As of 2012, 57% of women of child bearing age wanted to avoid pregnancy (867 of 1520 million). [ 5 ]  About 222 million women however were not able to access birth control, 53 million of whom were in sub-Saharan Africa and 97 million of whom were in Asia. [ 5 ]  Many countries limit access to birth control due to religious and political reasons. [ 6 ]


Contraceptive use among women in  Sub-Saharan Africa  has risen from about 5% in 1991 to about 30% in 2006. [ 7 ]  However, due to extreme  poverty , lack of access to birth control, and restrictive  abortion  laws, many women still resort to clandestine abortion providers for  unintended pregnancy , resulting in about 3% obtaining  unsafe abortions  each year. [ 8 ] [ 9 ]   South Africa ,  Botswana , and  Zimbabwe  have successful family planning programs, but other central and southern African countries continue to encounter extreme difficulties in achieving higher contraceptive prevalence and lower fertility for a wide variety of compounding reasons. [ 10 ]


The  one-child policy  of the  People's Republic of China  required couples to have no more than one child. Beginning in 1979, the policy was implemented to control rapid population growth. [ 11 ]  Chinese women receive free contraception and family planning services. [ 12 ]  Greater than 70% of those of childbearing age use contraception. [ 1 ]  Since the policy was put into place in 1979, over 400 million births have been prevented. [ 12 ]  Because of various exemptions, fertility rate is about 1.7 children per woman, down from 5.9 in the 1960s. A strong preference for boys and free access to fetus sex determination and abortion has resulted in an artificially high proportion of males in both rural and urban areas. [ 12 ]


Beginning January 1, 2016, China officially abolished the one-child policy. The Chinese government decided to allow families to have a second child to supposedly grow a bigger work force and allow the aging population to relax more. They predict that another economic boom will occur in the near future. The new policy was also seen as a solution to the massive gender disparity, with China's current population leaning heavily toward males. There are no concrete estimates for the new rate of growth of the Chinese population, but there are testimonies from the citizens about their new freedom. Some mothers have said that they are excited at the opportunity of having another child, while others still follow the one child tradition. [ 13 ]


Awareness of contraception is near-universal among married women in India. [ 14 ]  However, the vast majority of married Indians (76% in a 2009 study) reported significant problems in accessing a choice of contraceptive methods. [ 15 ]  In 2009, 48.3% of married women were estimated to use a contraceptive method, i.e. more than half of all married women did not. [ 15 ]  About three-fourths of these were using female sterilization, which is by far the most prevalent birth-control method in India. [ 15 ]  Condoms, at a mere 3%, were the next most prevalent method. [ 15 ]   Meghalaya ,  Bihar  and  Uttar Pradesh  had the lowest usage of contraception among all Indian states with rates below 30%. [ 15 ]


In 2011 just one in five Pakistani women aged 15 to 49 used modern birth control. [ 16 ]  In 1994,  Pakistan  pledged that by 2010 it would provide universal access to family planning. [ 17 ]  but contraception is shunned under traditional social norms. [ 16 ]  Most women who say they do not want any more children or would like to wait a period of time before their next pregnancy do not have the contraceptive resources available to them in order to do so. [ 17 ]  In the 1990s, women increasingly reported wanting fewer children, and 24 percent of recent births were reported to be unwanted or mistimed. [ 17 ]  The rate of  unwanted pregnancies  is higher for women living in poor or rural environments; with two-thirds of women live in rural areas. [ 17 ]  While 96 percent of married women were reported to know about at least one method of contraception, only half of them had ever used it. [ 17 ]  The most commonly reported reasons for married women electing not to use family planning methods include the belief that fertility should be determined by God (28%); opposition to use by the woman, her husband, others or a perceived religious prohibition (23%); infertility (15%); and concerns about health, side effects or the cost of family planning (12%). [ 17 ]


Contraception has been available for free under the  National Health Service  since 1974, and 74% of reproductive age women use some form of contraception. [ 18 ]  The levonorgestrel  intrauterine system  has been massively popular. [ 18 ]  Sterilization is popular in older age groups, among those 45-49, 29% of men and 21% of women have been sterilized. [ 18 ]  Female sterilization has been declining since 1996, when the intrauterine system was introduced. [ 18 ]   Emergency contraception  has been available since the 1970s, a product was specifically licensed for emergency contraception in 1984, and emergency contraceptives became available over the counter in 2001. [ 18 ]  Since becoming available over the counter it has not reduced the use of other forms of contraception, as some predicted it might. [ 18 ]  In any year only 5% of women of childbearing age use emergency hormonal contraception. [ 18 ]  Despite widespread availability of contraceptives, almost half of pregnancies were unintended circa 2005. [ 18 ]   Abortion  was legalized in 1967, however still remained illegal in Northern Ireland until 2020. [ 18 ]


As of 2008, in the United States, 99% of sexually active women have used birth control at some point in time. [ 19 ]  In 2015-2017, 64.9% of women aged 15-49 used a form of birth control. The most common forms of birth control were female sterilization (18.6%), oral contraceptive pills (12.6%), long-acting reversible contraceptives (10.3%), and male condoms (8.7%). [ 20 ]  Despite the availability of highly effective contraceptives, in 2011, 45% of pregnancies were unintended. [ 21 ]  In 2002, contraceptive use saved about $19 billion in direct medical costs. [ 22 ]


Prudence and the Pill  is a 1968 British  comedy film  made by  Twentieth Century-Fox . It was directed by  Fielder Cook  and  Ronald Neame  and produced by Kenneth Harper and Ronald J. Kahn from a screenplay by Hugh Mills, based on his 1965 novel. [ 3 ]  The music score was by Bernard Ebbinghouse and the cinematography by  Ted Moore .


The film stars  Deborah Kerr  and  David Niven  with  Robert Coote ,  Irina Demick ,  Joyce Redman ,  Judy Geeson ,  Keith Michell ,  Michael Hordern  and  Edith Evans .


Hayley Mills  was originally announced for the part eventually filled by Geeson. Mills had previously co-starred with Kerr and Evans in  The Chalk Garden  (1964), which was also directed by Neame.


The film portrays the conflicting and comical attempts by five couples to avoid  pregnancy  by using contraceptive pills. All of their efforts are ultimately unsuccessful, with the result that all five of the women give birth the following year.


The story revolves around a wealthy London banker named Gerald Hardcastle and his wife Prudence, who live together unhappily, sleeping in separate bedrooms and speaking to each other only when necessary. The five couples in the film are (1) Gerald and his French mistress Elizabeth, or "Liz", (2) Prudence and her doctor, Dr. Alan Huart, (3) the Hardcastles' maid Rose and their chauffeur Ted, (4) Gerald's brother Henry and his wife Grace, and (5) Henry's and Grace's daughter Geraldine and her beau Tony Bates.


All of the couples want to use a  birth control pill  called "Thenol", but none of them wants to admit it. Prudence, Grace, and Ted manage to acquire supplies of pills, Grace through a prescription written by Huart, and Ted from the local chemist, or pharmacist, who happens to be a friend of his. However, Grace soon becomes pregnant, because Geraldine has been stealing her pills and replacing them with  aspirin  tablets. After Geraldine admits her pill-switching scheme to Grace and Grace tells Gerald about it, Gerald uses the scheme on Prudence to generate incriminating evidence of her affair.


Meanwhile, believing that Rose is too conservative to accept contraception, Ted puts his tablets in a vitamin bottle and tells her she needs them for her health. However, Rose is worried about becoming pregnant, so she switches the pills in her vitamin bottle with the pills in Prudence's Thenol bottle, just moments after Gerald replaces Prudence's Thenol with aspirin. The result, then, is that Rose unwittingly trades Ted's Thenol for Gerald's aspirin. She soon becomes pregnant, and Ted tells Gerald about the pills he gave her, but says nothing about telling her they were vitamins. When Gerald asks her why her Thenol pills failed to work, she asks him how he knew about them, thinking that he has already found out about her taking Prudence's pills, at which point they both realise that she has revealed her guilt.


Now knowing why Prudence is still not pregnant, Gerald buys more aspirin, determined to expose her relationship with Huart. This eventually works, as do whatever measures Grace took to keep her pills away from Geraldine. By the end of the film, Geraldine and Prudence are both expecting.


Eventually, Gerald gets into trouble with both Liz and Prudence. Liz grows dissatisfied in her covert relationship with Gerald, who has been hiding her from his family, and decides to leave him. Prudence finds the letter that Liz wrote to Gerald about her decision, and Gerald finds Huart's Thenol prescription for Prudence. At first, neither Gerald nor Prudence is willing to grant the other a  divorce , but Prudence offers to take the blame after becoming pregnant, as long as Gerald will spare Huart's reputation. Gerald accepts this arrangement grudgingly, but before meeting with Huart, he happens to see Liz while driving through town, and she tells him she is going to have his baby. Now able to see her openly, and with a child on the way, Gerald quickly and enthusiastically agrees to an amicable divorce. A few months later, a total of six newborn babies arrive, Rose having had twins.


According to Fox records the film required $6,425,000 in rentals to break even and by 11 December 1970 had made $7,175,000. [ 4 ]  In September 1970 Fox reported it had made a profit on the film of $513,000. [ 5 ]


The Monthly Film Bulletin  wrote: "The only achievement of this dismal and unamusing comedy – completed by Ronald Neame after Fielder Cook overran his schedule – is that it manages to skirt the subject of contraception for ninety-two minutes without ever once generating any genuine sexiness or human sympathy. Its pseudomodernity is reflected in the pastiche Victorian Valentines of Richard Williams' title designs and in its inaccurate premise that the pill is available only to married women; and since each of its emancipated heroines manages – the pill notwithstanding – to get speedily pregnant, its portrayal of the new morality is unlikely to influence old-fashioned advocates of self-control." [ 6 ]


Rh factor testing , also known as Rhesus factor testing, is the procedure of determining the Rhesus D status of an individual (see  Rh blood group system ). [ 1 ] [ 2 ]


Rhesus factor testing utilizes  genotyping  to detect the presence of the  RhD gene . By checking the existence of the RhD gene in the individual's  genome , the presence of Rhesus D (RhD)  antigens  can be inferred. Individuals with a positive RhD status have RhD antigens expressed on the  cell membrane  of their  red blood cells , whereas Rhesus D antigens are absent for individuals with a negative RhD status.


Rhesus factor testing is usually performed on pregnant women to determine the RhD blood group of the mother and the fetus. By confirming the RhD status of both mother and fetus, precautions can be made, if necessary, to prevent any medical complications caused by Rhesus incompatibility.


The entire  Rh blood group system  involves multiple antigens and genes. For Rh factor testing, however, only the Rhesus factor correlated to the RhD antigen is assayed. The RhD gene that codes for the RhD antigen is located on  chromosome 1 . This chromosome contains gene instructions for making proteins in the body. [ 3 ]  RhD is a dominant gene, meaning that as long as at least one RhD gene is inherited from a single parent, the RhD antigen is expressed. Vice versa, if no RhD gene is inherited from either parent, no RhD antigen is produced.


Non-invasive extraction


Blood plasma  is commonly used as test samples for verifying the maternal RhD status. Blood plasma can also be used for determining the fetal RhD status if the mother is RhD- as maternal blood plasma contains maternal  DNA  and trace amounts of fetal DNA. In early pregnancy, around 3% of the mother’s free-cell DNA is from the fetus, and raises to 6-7% by late pregnancy. [ 4 ]  Blood samples can be obtained through  venipuncture  of the mother. Since plasma and other components of blood have different densities,  centrifugation  of blood samples with added  anticoagulant  (such as  EDTA ) can segregate blood contents into multiple layers. Blood plasma can then be isolated from the other components. It can be genotyped using real time PCR to determine the RhD status of the fetus. [ 4 ]  The method of extracting fetal DNA from maternal blood plasma is considered to be a type of non-invasive  prenatal testing .


Non-invasive  prenatal testing  can be used if the mother is RhD-. However, in the case of maternal RhD status being positive, invasive prenatal testing may be used to determine the fetal RhD status instead. The two most common invasive methods of extracting fetal DNA are  chorionic villus sampling  (CVS) and  amniocentesis  (AMC). These invasive procedures can be conducted on both RhD+ and RhD- mothers. After the invasive procedure, medications that prevent the Rh  immunization  are usually prescribed to RhD- mothers. This is done to avoid the production of maternal anti-D  antibodies  which may attack the fetal blood cells should the fetus be Rh incompatible with the mother.


Chorionic villus sampling  is usually performed between the 10th and 13th week of pregnancy. It samples  chorionic villi , which are tiny projections of  placental tissue . The placental tissues are derived from  embryonic cells , hence, they contain fetal genetic information that can be used to determine the child's RhD status. There are two types of chorionic villus sampling. Trans-cervical sampling involves inserting a  catheter  through the  cervix  into the  placenta  to obtain villi; an  ultrasound  is used to guide the catheter to the site of sampling. Trans-abdominal sampling requires the insertion of a needle through the  abdomen  and  uterus  to obtain placental tissue.  Local anesthesia  can be applied to reduce the pain from  invasive procedures .


Amniocentesis  is another invasive procedure which can be used to collect fetal DNA samples. [ medical citation needed ]  This procedure is usually done between the 15th and 20th week of  pregnancy . The purpose of AMC is to extract a small amount of  amniotic fluid  as fetal cells may be shed from the fetus and are suspended in the amniotic fluid. Since the fetal genome can be found in these cells, extracting amniotic fluid provides the required fetal genetic material for the genotyping of the RhD gene. Before amniocentesis commences, the doctor will inject local anesthetics to the mother's abdomen. The doctor will then use an ultrasound to locate the fetus in the uterus. Under the guidance of the  ultrasound imaging , a long, thin, hollow needle will be inserted through the skin of the abdomen to the uterus of the mother. The needle is used to withdraw a trace amount of amniotic fluid. It is then removed from the maternal body and the extracted amniotic fluid is sent to the laboratory for further testing.


The presence of the RhD gene in an individual's genome is determined by  genotyping . Firstly, the body fluid containing an individual's DNA will be extracted. DNA will then be isolated from unwanted impurities. The isolated DNA will then be mixed with various reagents to prepare the  polymerase chain reactions  (PCR) mixture. The PCR mixture usually contains  Taq DNA polymerase ,  DNA primers ,  deoxyribonucleotides  (dNTP) and  buffer solution . The DNA primers are specific for  exon  7 and exon 10. Under different circumstances, primers for other regions of the RhD gene, such as  intron  4 and exon 5, may also be used. The mixture will be subjected to a series of PCR which is performed by a  thermal cycler . By the end of the PCR process, the amount of RhD gene will be amplified if it is present. The product of the PCR will be analyzed by  gel electrophoresis . Before gel electrophoresis,  DNA reference ladder , a  positive control  containing DNA with RhD gene, and the PCR product will be loaded onto the wells of the gel. An  electric current  will be applied and the DNA fragments will migrate to the positive terminal as they are negative in charge. Since DNA fragments have different molecular sizes, the larger they are, the slower they migrate. Utilizing this property, DNA fragments with different molecular masses can be segregated. With the help of gel staining and visualizing devices such as  UV trans-illuminators , RhD gene DNA fragments, if present, will be visible as a band with its corresponding molecular mass. Further DNA sequencing can be conducted to confirm that the sequence of product DNA fragments matches that of the RhD gene sequence.


Rh factor testing is crucial to prevent haemolytic conditions caused by the Rh incompatibility. [ citation needed ]  The consequence of having haemolytic conditions can be dangerous or even lethal as it may lead to multiple complications. Not only does Rh factor testing determine the rhesus status of the individuals, but also indicate the necessity for further medical intervention.


When RhD antigens on red blood cells are exposed to an individual with RhD- status, high-frequency of  IgG   anti-RhD   antibodies  will be developed in the RhD- individual's body. The antibodies then attack red blood cells with attached RhD  antigens  and lead to the destruction of these cells. This condition is known as a  haemolytic reaction . The destruction of red blood cells releases  hemoglobin  to the bloodstream. Hemoglobin may be excreted through  urine , causing  haemoglobinuria . The sudden release of hemoglobin will also pass through the liver and be metabolized into  bilirubin , which in high concentrations, accumulates under the skin to cause  jaundice . Liberation of blood cell debris into the circulation will also cause  disseminated intravascular coagulation .


Patients receiving incompatible  blood transfusion  may have pale skin,  splenomegaly ,  hepatomegaly  and the yellowing of mouth and eyes. In addition, their urine may appear in dark color and the patients may experience dizziness and confusion.  Tachycardia , the increase in heart rate, is also a symptom of the haemolytic disease.


In the case of pregnancy, when an RhD- mother carries an RhD+ fetus, some of the fetal red blood cells may cross the placenta into the maternal circulation, sensitizing the mother to produce anti-RhD antibodies. Since the mixing of fetal and maternal blood occurs mainly during separation of the placenta during delivery, the first RhD+ pregnancy rarely causes any danger to the fetus as delivery occurs before the synthesis of antibodies by the mother. However, if the mother were to conceive another RhD+ child in the future, the anti-RhD antibodies will cross the placenta to attack and lyse the red cells of the fetus, causing the aforementioned haemolytic reaction in the fetus known as  haemolytic disease of the newborn . This disease is usually fatal for the fetus and hence preventive measures are conducted.


Symptoms of the disease may vary in each pregnancy. They are usually not noticeable during pregnancy. However, prenatal tests may reveal yellow colouring of amniotic fluid, which is caused by the buildup of bilirubin. [ 5 ]  Splenomegaly,  cardiomegaly  and hepatomegaly may occur in the baby. [ 5 ]  Excessive  tissue fluid  may accumulate in the  stomach ,  lungs  or  scalp . These are typically signs of  hydrops fetalis . [ 5 ]


After birth, the symptoms of the child are similar to that of incompatible blood transfusion in adults.  The baby may have pale skin due to  anaemia . The yellowing of the  umbilical cord , skin and eyes, also known as jaundice, may arise within 24 to 36 hours of birth. [ 5 ]  Signs of hydrops fetalis such as the enlargement of  spleen ,  heart  and  liver , along with severe  edema , will continue after birth. [ 5 ]


Normally, no extra medical intervention is required when maternal Rh status is RhD+, nor RhD- mothers going through first pregnancy. However, in the case of a sensitized RhD- mother (previously conceived an RhD+ child) and the fetus being Rh+, medication such as an  anti-D immunoglobulin , called RhoGAM, will be given to the RhD- mother. Injecting RhD- mother with RhoGAM has been proven effective in avoiding the sensitisation of RhD+ antigen, even though the mechanism of how this medication works remains obscure.


This injection is given to the RhD- mother during the second trimester when there is incompatibility between her and the father. Another injection is given a couple days after delivery if the baby is found to be RhD+.  These injections may also be given to RhD- mothers after a miscarriage/abortion,after injury to the abdomen, or after the prenatal tests mentioned before of amniocentesis and chorionic villus sampling (cite1).   Anti-D immunoglobulin injection is also offered to RhD- individuals who have been mistakenly transfused with RhD+ blood.


Safe sex  is  sexual activity  using methods or contraceptive devices (such as  condoms ) to reduce the risk of transmitting or acquiring  sexually transmitted infections  (STIs), especially  HIV . [ 1 ]  "Safe sex" is also sometimes referred to as  safer sex  or  protected sex  to indicate that some safe sex practices do not eliminate STI risks. It is also sometimes used colloquially to describe methods aimed at  preventing pregnancy  that may or may not also lower STI risks.


The concept of "safe sex" emerged in the 1980s as a response to the global  AIDS epidemic , and possibly more specifically to the  AIDS crisis  in the  United States . Promoting safe sex is now one of the main aims of  sex education  and STI prevention, especially reducing new HIV infections. Safe sex is regarded as a  harm reduction  strategy aimed at reducing the risk of STI transmission. [ 2 ] [ 3 ]


Although some safe sex practices (like  condoms ) can also be used as  birth control  ( contraception ), most forms of contraception do not protect against STIs. Likewise, some safe sex practices, such as partner selection and low-risk sex behavior, [ example needed ]  might not be effective forms of contraception.


Although strategies for avoiding STIs like  syphilis  and  gonorrhea  have existed for centuries and the term "safe sex" existed in English as early as the 1930s, the use of the term to refer to STI-risk reduction dates to the mid-1980s in the United States. It emerged in response to the  HIV/AIDS crisis . [ 4 ] [ 5 ]


A year before the HIV virus was isolated and named, the San Francisco chapter of the  Sisters of Perpetual Indulgence  published a small pamphlet titled  Play Fair!  out of concern over widespread STIs among the city's gay male population. It specifically named illnesses (Kaposi's sarcoma and pneumocystis pneumonia) that would later be understood as symptoms of advanced HIV disease (or  AIDS ). The pamphlet advocated a range of safe-sex practices, including abstinence, condoms, personal hygiene, use of personal lubricants, and STI testing/treatment. It took a casual, sex-positive approach while also emphasizing personal and social responsibility. In May 1983—the same month HIV was isolated and named in France—the New York City-based HIV/AIDS activists Richard Berkowitz and Michael Callen published similar advice in their booklet,  How to Have Sex in an Epidemic: One Approach . Both publications included recommendations that are now standard advice for reducing STI (including HIV) risks. [ 6 ] [ 7 ] [ 8 ]


Safe sex as a form of STI risk reduction appeared in journalism as early as 1984, in the British publication  The Daily Intelligencer : "The goal is to reach about 50 million people with messages about safe sex and AIDS education." [ 5 ]


Although  safe sex  is used by individuals to refer to protection against both  pregnancy  and HIV/AIDS or other STI transmissions, the term was born in response to the HIV/AIDS epidemic. It is believed that the term  safe sex  was used in the professional literature in 1984, in the content of a paper on the psychological effect that HIV/AIDS may have on gay and bisexual men. [ 9 ]


A year later, the same term appeared in an article in  The New York Times .  This article emphasized that most specialists advised their AIDS patients to practice safe sex. The concept included limiting the number of sexual partners, using prophylactics, avoiding bodily fluid exchange, and resisting the use of  drugs  that reduced inhibitions for high-risk sexual behavior. [ 10 ]  Moreover, in 1985, the first safe sex guidelines were established by the 'Coalition for Sexual Responsibilities'. [ who? ]  According to these guidelines, safe sex was practiced by using  condoms  also when engaging in  anal  or  oral sex . [ 11 ]


Although the term  safe sex  was primarily used in reference to sexual activity between men, in 1986 the concept was spread to the general population. Various programs were developed with the aim of promoting safe sex practices among college students. These programs were focused on promoting the use of the condom, a better knowledge about the partner's sexual history and limiting the number of  sexual partners . The first book on this subject appeared in the same year. The book was entitled "Safe Sex in the Age of AIDS", and had 88 pages that described both positive and negative approaches to sexual life. [ citation needed ]  Sexual behavior could be safe ( kissing ,  hugging ,  massage ,  body-to-body rubbing ,  mutual masturbation ,  exhibitionism ,  phone sex , and use of separate  sex toys ); possibly safe (use of condoms); or unsafe. [ 10 ]


In 1997, specialists in this matter promoted the use of condoms as the most accessible safe sex method (besides abstinence) and they called for  TV commercials  featuring condoms. During the same year, the  Catholic Church  in the United States issued their own "safer sex" guidelines on which condoms were listed, though two years later the  Vatican  urged  chastity  and  heterosexual  marriage, attacking the American Catholic bishops' guidelines. [ citation needed ]


A study carried out in 2006 by Californian specialists showed that the most common definitions of safe sex are condom use (68% of the interviewed subjects), abstinence (31.1% of the interviewed subjects), monogamy (28.4% of the interviewed subjects) and safe partner (18.7% of the interviewed subjects). [ 10 ]


The term  safer sex  in Canada and the United States has gained greater use by health workers, reflecting that risk of transmission of sexually transmitted infections in various  sexual activities  is a  continuum . The term  safe sex  is still in common use in the United Kingdom, [ 12 ]  Australia and New Zealand.


"Safer sex" is thought to be a more aggressive term which may make it more obvious to individuals that any type of sexual activity carries a certain degree of risk.


The term  safe love  has also been used, notably by the French  Sidaction  in the promotion of men's underpants incorporating a condom pocket and including the red ribbon symbol in the design, which were sold to support the charity.


A range of safe-sex practices are commonly recommended by Sexual Health Educators and Public Health Agencies. Many of these practices can reduce (but not eliminate) risk of transmitting or acquiring STIs. [ 13 ]


Sexual activities, such as phone sex,  cybersex , and  sexting , that do not include direct contact with the skin or bodily fluids of sexual partners, carry no STI risks and, thus, are forms of safe sex. [ 14 ]


A range of sex acts called "non-penetrative sex" or "outercourse" can significantly reduce STI risks. Non-penetrative sex includes practices such as kissing, mutual masturbation, manual sex, rubbing or stroking. [ 15 ] [ 16 ]  According to the Health Department of Western Australia, this sexual practice may prevent pregnancy and most STIs. However, non-penetrative sex may not protect against infections that can be transmitted via skin-to-skin contact, such as  herpes  and  human papilloma virus . [ 17 ]  Mutual masturbation and manual sex carry some STI risk, especially if there is skin contact or shared bodily fluids with sexual partners, although the risks are significantly lower than many other sexual activities. [ 14 ]


Barriers, such as condoms, dental dams, and medical gloves can prevent contact with body fluids (such as  blood ,  vaginal fluid ,  semen , rectal mucus), and other means of transmitting STIs (like skin, hair and shared objects) during sexual activity. [ 18 ] [ 19 ]


Oil-based  lubrication  can break down the structure of latex condoms, dental dams or gloves, reducing their effectiveness for STI protection. [ 22 ]


While use of external condoms can reduce STI risks during sexual activity, they are not 100% effective. One study has suggested condoms might reduce HIV transmission by 85% to 95%; effectiveness beyond 95% was deemed unlikely because of slippage, breakage, and incorrect use. [ 23 ]  It also said, "In practice, inconsistent use may reduce the overall effectiveness of condoms to as low as 60–70%". [ 23 ] p. 40.


Pre-exposure prophylaxis  (often abbreviated as  PrEP ) is the use of prescription drugs by those who do not have HIV to prevent HIV infection. PrEP drugs are taken  prior  to HIV exposure to prevent the transmission of the virus, usually between sexual partners. PrEP drugs do not prevent other STI infections or pregnancy. [ 24 ]


As of 2018, the most-widely approved form of  PrEP  combines two drugs (tenofovir and emtricitabine) in one pill. That drug combination is sold under the brand name  Truvada  by Gilead Sciences. It is also sold in generic formulations worldwide. Other drugs and modalities are being studied for use as PrEP. [ 25 ] [ 26 ]


Different countries have approved different protocols for using the tenofovir/emtricitabine-combination drug as  PrEP . That two-drug combination has been shown to prevent HIV infection in different populations when taken daily, intermittently, and on demand. Numerous studies have found the tenofovir/emtricitabine combination to be over 90% effective at preventing HIV transmission between sexual partners. [ 27 ]  AVAC has developed a tool to track trends in PrEP uptake across the globe. [ 28 ]


Treatment as Prevention (often abbreviated as  TasP ) is the practice of testing for and treating HIV infection as a way to prevent further spread of the virus. Those having knowledge of their HIV-positive status can use safe-sex practices to protect themselves and their partners (such as using condoms, sero-sorting partners, or choosing less-risky sexual activities). And, because HIV-positive people with durably suppressed or undetectable amounts of HIV in their blood  cannot transmit HIV to sexual partners , sexual activity with HIV-positive partners on effective treatment is a form of safe sex (to prevent HIV infection). This fact has given rise to the concept of "U=U" ("Undetectable = Untransmittable"). [ 29 ]


Other methods proven effective at reducing STI risks during sexual activity are:


Most methods of contraception are not effective at preventing the spread of  STIs . This includes  birth control pills ,  vasectomy ,  tubal ligation ,  periodic abstinence ,  IUDs  and many non-barrier methods of pregnancy prevention. However,  condoms , when used correctly, significantly reduces the risks of STI transmission and unwanted pregnancy. [ 39 ]


The  spermicide   nonoxynol-9  has been claimed to reduce the likelihood of STI transmission. However, a technical report from 2001 [ 40 ]  by the  World Health Organization   has shown that nonoxynol-9 is an irritant and can produce tiny tears in mucous membranes, which may increase the risk of transmission by offering  pathogens  more easy points of entry into the system. They reported that nonoxynol-9 lubricant do not have enough spermicide to increase contraceptive effectiveness cautioned they should not be promoted. There is no evidence that spermicidal condoms are better at preventing STD transmission compared to condoms that do not have spermicide. If used properly, spermicidal condoms can prevent pregnancy, but there is still an increased risk that nonoxynyl-9 can irritate the skin, making it more susceptible for infections. [ 40 ] [ 41 ]


The use of a  diaphragm  or  contraceptive sponge  provides some women with better protection against certain sexually transmitted infections, [ 42 ]  but they are not effective for all STIs.


Hormonal methods of preventing pregnancy (such as oral contraceptives [i.e. 'The pill'], depoprogesterone, hormonal IUDs, the vaginal ring, and the patch) offer no protection against STIs. The copper intrauterine device and the hormonal intrauterine device provide an up to 99% protection against pregnancies but no protection against STIs. Women with copper intrauterine device  may  be subject to greater risk of infection from bacterial infectious such as  gonorrhea  or  chlamydia , although this is debated. [ 43 ]


Coitus interruptus  (or "pulling out"), in which the penis is removed from the  vagina  or  mouth  before  ejaculation , may reduce transmission of STIs but still carries significant risk. This is because  pre-ejaculate , a fluid that oozes from the penile  urethra  before ejaculation, may contain STI pathogens. Additionally, the microbes responsible for some diseases, including  genital warts  and  syphilis , can be transmitted through skin-to-skin or mucous membrane contact. [ 44 ]


Unprotected  anal penetration  is considered a high-risk sexual activity because the thin tissues of the anus and  rectum  can be easily damaged. [ 45 ] [ 46 ]   Slight injuries can allow the passage of bacteria and viruses, including HIV. This includes penetration of the anus by fingers, hands, or sex  toys  such as  dildos . Also, condoms may be more likely to break during anal sex than during vaginal sex, increasing the risk of STI transmission. [ 47 ]


The main risk that individuals are exposed to when performing anal sex is the transmission of  HIV . Other possible infections include  hepatitis A ,  B  and  C ;  intestinal parasite infections  like  Giardia ; and bacterial infections such as  Escherichia coli . [ 48 ]


Anal sex should be avoided by couples in which one of the partners has been diagnosed with an STI until the treatment has proven to be effective.


In order to make anal sex safer, the couple must ensure that the anal area is clean and the bowel empty and the partner on whom anal penetration occurs should be able to relax. Regardless of whether anal penetration occurs by using a finger or the penis, the condom is the best barrier method to prevent transmission of STI.  Enemas  should not be used as they can increase the risk of HIV infection [ 49 ]  and  lymphogranuloma venereum   proctitis . [ 50 ]


Since the rectum can be easily damaged, the use of lubricants is highly recommended even when penetration occurs by using the finger. Especially for beginners, using a condom on the finger is both a protection measure against STI and a lubricant source. Most condoms are lubricated and they allow less painful and easier penetration. Oil-based lubricants damage latex and should not be used with condoms; [ 51 ]  water-based and silicone-based  lubricants  are available instead. Non-latex condoms are available for people who are  allergic to latex  made out of  polyurethane  or  polyisoprene . [ 52 ]  Polyurethane condoms can safely be used with oil-based lubricant. [ 53 ]  The " female condom " may also be used effectively by the anal receiving partner.


Anal stimulation with a sex toy requires similar safety measures to anal penetration with a penis, in this case using a condom on the sex toy in a similar way.


It is important that the man washes and cleans his penis after anal intercourse if he intends to penetrate the vagina. Bacteria from the rectum are easily transferred to the vagina, which may cause  vaginal  and  urinary tract infections . [ 54 ]


When anal–oral contact occurs, protection is required since this is a  risky sexual behavior  in which illnesses such as hepatitis A or STIs can be easily transmitted, as well as enteric infections. The dental dam or plastic wrap [ 55 ]  are effective protection means whenever anilingus is performed.


Putting a condom on a  sex toy  provides better sexual hygiene and can help to prevent transmission of infections if the sex toy is shared, provided the condom is replaced when used by a different partner. Some  sex toys  are made of porous materials, and pores retain viruses and bacteria, which makes it necessary to clean sex toys thoroughly, preferably with use of cleaners specifically for sex toys. Glass is non-porous and medical grade glass sex toys more easily sterilized between uses. [ 56 ]


In cases in which one of the partners is treated for an STI, it is recommended that the couple not use sex toys until the treatment has proved to be effective.


All sex toys have to be properly cleaned after use. The way in which a sex toy is cleaned varies on the type of material it is made of. Some sex toys can be boiled or cleaned in a dishwasher. Most of the sex toys come with advice on the best way to clean and store them and these instructions should be carefully followed. [ 57 ]  A sex toy should be cleaned not only when it is shared with other individuals but also when it is used on different parts of the body (such as mouth, vagina or anus).


A sex toy should regularly be checked for scratches or breaks that can be breeding ground for  bacteria . It is best if the damaged sex toy is replaced by a new undamaged one. Even more  hygiene  protection should be considered by pregnant women when using sex toys. Sharing any type of sex toy that may draw  blood , like whips or needles, is not recommended, and is not safe. [ 57 ]


When using sex toys in the anus, sex toys "...can easily get lost" as "rectal muscles contract and can suck an object up and up, potentially obstructing the colon"; to prevent this serious problem, sex toy users are advised to use sex "...toys with a flared base or a string". [ 58 ]


Sexual abstinence  reduces STIs and pregnancy risks associated with  sexual contact , but STIs may also be transmitted through non-sexual means, or by  rape . HIV may be transmitted through contaminated needles used in  tattooing ,  body piercing , or  injections . Medical or dental procedures using contaminated instruments can also spread HIV, while some health-care workers have acquired HIV through occupational exposure to accidental injuries with needles. [ 59 ]  Evidence does not support the use of  abstinence-only sex education . [ 60 ]  Abstinence-only sex education programs have been found to be ineffective in decreasing rates of  HIV  infection in the developed world [ 61 ]  and  unplanned pregnancy . [ 60 ]  Abstinence-only sex education primarily relies on the consequences of character and morality while health care professionals are concerned about matters regarding health outcomes and behaviors. [ 62 ]  Though abstinence is the best course to prevent pregnancy and STIs, in reality, it leaves young people without the information and skills they need to avoid unwanted pregnancies and STIs. [ 62 ]


Slut-shaming  is the practice of criticizing people who violate expectations of behavior and appearance regarding issues related to  sexuality . [ 1 ] [ 2 ] [ 3 ]  It may also be used in reference to  gay men , who may face disapproval for  promiscuous  sexual behaviors. [ 1 ] [ 4 ]  Gender-based violence primarily affecting women can be a result of slut-shaming. [ 5 ]  The term is commonly used to reclaim the word  slut  and empower women to have  agency  over their own sexuality. [ 3 ]


Examples of slut-shaming include criticism or punishment for: violating  dress code  policies by dressing in  sexually provocative  ways; requesting access to  birth control ; [ 6 ] [ 7 ] [ 8 ]  having  premarital ,  extramarital ,  casual , or  promiscuous  sex; or engaging in  prostitution  or other  sex work . [ 9 ] [ 10 ]  It can also include being  victim-blamed  for being  raped  or otherwise  sexually assaulted . [ 11 ] [ 12 ]


Slut-shaming involves criticizing women for their transgression of accepted codes of sexual conduct, [ 13 ]  i.e., admonishing them for behavior, attire or desires that are more sexual than society finds acceptable. [ 14 ] [ 15 ] [ 16 ] [ 17 ]  Author Jessalynn Keller stated, "The phrase [slut-shaming] became popularized alongside the  SlutWalk  marches and functions similarly to the ' War on Women ,' producing affective connections while additionally working to reclaim the word 'slut' as a source of power and agency for girls and women." [ 3 ]


Slut-shaming may be practiced by men and women. [ 18 ] [ 19 ]  Women who slut-shame other women continuously apply unfavorable sexual double standards. [ 20 ]  The term is also used to describe  victim blaming  for  rape  and other  sexual assault . This blaming is done by stating the crime was caused (either in part or in full) by the woman wearing  revealing clothing  or acting in a  sexually provocative  manner, before refusing consent to sex, [ 11 ]  thereby absolving the perpetrator of guilt. Sexually lenient individuals can be at risk of social isolation. [ 21 ]


Kennair, et al., (2023) found no signs of a sexual  double standard  in short-term or long-term mating contexts, nor in choosing friends, except that, contrary to expectations, women's  self-stimulation  was more acceptable than men's. [ 22 ]


The action of slut-shaming can be a form of social punishment and is an aspect of  sexism , as well as  female intrasexual competition . Slut-shaming is a form of intrasexual competition because the term "slut" reduces the value of a woman. Being termed a "slut" is against a woman's gender norms. [ 23 ]


Researchers from Cornell University found that sentiments similar to slut-shaming appeared in a nonsexual, same-sex friendship context as well. [ 21 ]  The researchers had college women read a vignette describing an imaginary female peer, "Joan", then rate their feelings about her personality. [ 21 ]  To one group of women, Joan was described as having two lifetime sexual partners; to another group, she had had 20 partners. [ 24 ]  The study found that women—even women who were more promiscuous themselves—rated the Joan with 20 partners as "less competent, emotionally stable, warm, and dominant" than the Joan with two. [ 21 ] [ 24 ]


There is no documented date of origin for the term  slut-shaming ; nor the act of it. Rather, although the act of slut-shaming has existed for centuries, discussion of it has grown out of social and cultural relations and the trespassing of boundaries of what is considered normative and acceptable behavior. While the origin is unknown, by the late 2000s, the term was popular enough to merit usage in newspaper articles. American writer  Katha Pollitt , in an article published in March 2008, used the term the following way: “the abstinence only, father-knows-best, slut-shaming crabbed misogyny of the Republican right.” [ 25 ]


Before the late 2000s, the term “slutty” was sometimes used to refer to behavior considered to be unacceptable such as the 2000s trend of showing off one’s  thong underwear  to create a  whale tail . In 2005,  Suzy Menkes , a veteran journalist covering the fashion industry, considered the act of revealing thongs above one's clothing to be “slutty chic” and hoped that the act would lose popularity. [ 26 ]


Literary characters who were killed or died by suicide as a result of their sexual choices include  Ophelia  of  Hamlet  ( c.  1600 ); Little Em'ly of  David Copperfield  (1850);  Hester Prynne  of  The Scarlet Letter  (1850);  Madame Bovary  (1856);  Anna Karenina  (1878);  Daisy Miller  (1878);  Tess of the d'Urbervilles  (1891); Lily Bart of  House of Mirth  (1905); and Charity Royall in  Summer  (1917). [ 27 ]


In 1892, Canadian writer  E. Pauline Johnson  criticized the 1887 novel  An Algonquin Maiden  for killing its protagonist and having male characters posthumously label her a " squaw ," a racial and sexual slur that displayed "glaring accusations against her virtue," which Johnson felt was undeserved. [ 28 ]


Beginning in the 1960s,  second-wave feminism  contributed significantly to the definition and act of slut-shaming. Tracing back to the  Industrial Revolution  and the  Second World War , men made up a majority of the labor force while women were socialized and taught to embrace the cult of domesticity and homemaking. [ 29 ]  Author Emily Poole argues that the sexual revolution of the 1960s and 1970s increased the rate of both  birth control  use and  premarital sex . [ 29 ]  Moreover, feminist writers during the 1960s and 1970s such as Betty Friedan, Gloria Steinem, and Kate Millett encouraged women to be more open about their sexuality in public settings. [ 30 ]


Slut-shaming has correlation to an individual's socio-economic status, which is characterized by wealth, education, and occupation. In the 18th century, "slut" was a common term used by men and upper-class women to degrade lower-class female servants. [ 23 ]  The context behind upper-class women and men calling their servants a "slut" includes when the servants were being sexually assaulted by their male employers.


Slut-shaming is prevalent on  social media  platforms, including the most commonly used:  YouTube ,  Instagram ,  Twitter , and  Facebook . Slut-shaming has occurred on Facebook in controversial exchanges between users that have resulted in convictions to menace, harass and cause offense. [ 31 ] [ 32 ]


In 2014,  The Pew Research Center  reported the most common targets of harassment on the Internet are often young women. Citing that 50% of young female respondents have been called offensive names and or shamed online. In particular, those who were 18 to 24 years of age experienced varying amounts of severe harassment at astoundingly high rates. Women who have been stalked online were at 26%, while the targets of online sexual harassment were at 25%. [ 33 ]


In the  Women Studies International Forum , researcher Jessica Megarry used the Twitter  hashtag campaign  #mencallmethings as a case study of online sexual harassment. [ 34 ]  Women used the hashtag to report harassment they received from men, including insults related to appearance, name calling, rape threats, and death threats. [ 34 ] [ 35 ]


In 2011, the  SlutWalk  protest march originated in  Toronto  in response to an incident when a Toronto Police officer told a group of students that they could avoid sexual assault by not dressing like "'sluts'". [ 11 ] [ 36 ] [ 37 ] [ 38 ]


Amber Rose 's second annual walk in Los Angeles in 2016 had "several hundred" participants. [ 39 ]  A similar event occurred in Washington DC in 2014. [ 40 ]


The Slut Walk movement has embraced the slut-shame label and has engaged in an act of resignification. Ringrose et al. call the Slut Walk a "collective movement" where the focus goes back to the perpetrator and no longer rests on the victim. [ 36 ]  This act of resignification comes from the work of feminist scholar  Judith Butler . In her 1997 work, she argued that labels do not just name and marginalize individuals to categories, but also open up an opportunity for resistance. [ 41 ]


Krystal Ball characterized the comments of  Rush Limbaugh  during the  Rush Limbaugh–Sandra Fluke controversy  as follows: "If you are a woman who stands up for your rights, you are a slut and your parents should be ashamed of you and we should all have the right to view your sex tapes online. This type of despicable behavior is part and parcel of a time-worn tradition of Slut-Shaming. When women step out line [sic], they are demeaned and degraded into silence. If you say Herman Cain sexually harassed you, you are a slut. If you say Supreme Court Justice Clarence Thomas sexually harassed you, you are a slut." [ 42 ] [ 8 ]


Slut-shaming has been used as a form of bullying on social media, with some people using  revenge pornography  tactics to spread intimate photos without consent. In 2012, a teenager from California,  Audrie Pott , was sexually assaulted by three boys at a party. She committed suicide eight days after photos of her being assaulted were distributed among her peer group. [ 43 ]


James Miller, editor-in-chief of the  Ludwig von Mises Institute  of Canada, wrote a controversial article defending slut shaming. [ 44 ]  The article was later taken down, but still received criticism from some libertarians, such as Gina Luttrell of  Thoughts on Liberty , an all-female  libertarian  blog. [ 45 ]


Comedians Krystyna Hutchinson and Corinne Fischer of  Sorry About Last Night  host a podcast entitled  Guys We Fucked, The Anti-slut shaming podcast . [ 46 ] [ 47 ]  This podcast has over 200,000 listeners on each episode that is on SoundCloud. [ 48 ]  The podcast exists to de-stigmatize discussing sex so that slut-shaming becomes less of an issue. Hutchinson told  The Huffington Post : "We want to make people feel more comfortable in their own skin. We just got a message from a girl from New Delhi, India, about how she loves the podcast because it makes her feel like it's OK to be comfortable with your sexuality and enjoy sex. And that made me so happy". [ 42 ]


Activism against slut-shaming takes place worldwide. Participants have covered their bodies in messages reading "Don't Tell Me How to Dress" and "I am not a slut but I like having consensual sex" and march under a giant banner with the word slut on it. Activism has occurred in Vancouver, New York City, Rio, Jerusalem, Hong Kong, and others. [ 49 ]


In 2008, hundreds of South African women protested at the local taxi rank wearing miniskirts and t-shirts that read, "Pissed-Off Women" after a taxi driver and multiple hawkers confronted a young girl about wearing a short denim miniskirt and penetrated her with their fingers, calling her "slut" repeatedly. Protesters wanted to make their message clear; they wanted men to stop harassing women, no matter how short their skirts were and that no matter how short it may be, it is never an invitation. [ 50 ]


After the  gang rape of an unconscious 16-year-old girl  in  Steubenville, Ohio , August 2012, football players spread videos of the assault to other classmates, some of whom posted the videos to Twitter and Instagram. The pictures and video were later removed by authorities; however, that did not stop people from hash-tagging "Whore status" or "I have no sympathy for whores" in their tweets. Members of the collective  Anonymous  reported names of the rapists and classmates who spread the footage to local authorities. They took to the streets and internet requesting help from the community to bring justice to the  Jane Doe  who was raped. [ 51 ]