Pelvic pain that is unrelated to pregnancy may be caused by ovulation or dysmenorrhea. Pain around the time of ovulation can occur for a few hours and may last 2 days.


Dysmenorrhea is severe pain caused by menstrual cramps. It is theorized that excess prostaglandin causes smooth muscle contractions, leading to dysmenorrhea. These painful menses are typically observed in the first five years of ovulatory menstrual cycles, and improve with age. Dysmenorrhea affects over 50% of all post-pubescent women. To manage the pain, prostaglandin inhibition or the suppression of cycles is sought. Other methods for managing the pain include the use of heat, mild analgesics, and exercise.


Pelvic inflammatory disease (PID) is an infection affecting the female reproductive system, typically resulting from pelvic infections transmitted through sexual contact, such as gonorrhea or chlamydia. The use of an intrauterine device (IUD) for contraception can also elevate the risk of PID. On the other hand, oral contraception may offer some protection, as it disrupts cervical secretions and hinders the attachment of these organisms to endometrial cells. PID, if left untreated, can lead to severe complications, including chronic pain, infertility, ectopic pregnancies, and, in extreme cases, even death.


Endometriosis is when tissue that normally lines the endometrium grows outside of the uterus, causing pelvic pain (See Figure 1). This can occur at any time throughout female reproductive years.


Endometriosis can cause cyclic pain, dysmenorrhea, and severe dyspareunia, or painful intercourse. If a female has endometriosis, she has a 30-40% chance of being infertile. Endometriosis can cause a female to become infertile by trapping the ovum, or the cytokine and prostaglandin production that may interrupt the ovulation, tubal function, and luteal phase detection. Management of endometriosis typically involves treatment through hormonal therapies or excision surgery.


Reproductive tumors, such as ovarian (or testicular in males), uterine, or cervical tumors, can lead to pelvic pain.  Several treatment options are available for reproductive tumors, including surgery, chemotherapy, radiation therapy, and targeted therapy. The choice of treatment depends on many factors, like the type and stage of the tumor, the patient’s overall health, and individual preferences. It is paramount to stress the significance of early detection via regular screenings, immunization, and vaccination. Additionally, a proactive approach to understanding one’s genetic predisposition and making lifestyle choices conducive to overall well-being can considerably reduce the risk of reproductive tumors and enhance long-term health.


It is paramount to stress the significance of early detection via regular screenings, immunization, and vaccination. Additionally, a proactive approach to understanding one’s genetic predisposition and making lifestyle choices conducive to overall well-being can considerably reduce the risk of reproductive tumors and enhance long-term health.


Pelvic pain in females related to pregnancy can be attributed to conditions such as abortions or ectopic pregnancies.


Miscarriage, also referred to as pregnancy loss, is the spontaneous termination of a pregnancy before reaching the 20th week of gestation. It affects approximately 10-20% of known pregnancies and can occur due to various factors, including chromosomal irregularities, hormonal imbalances, and specific health conditions.


Symptoms of a miscarriage often include pelvic discomfort, which may range from mild to severe and is frequently accompanied by bleeding. Bleeding is a prevalent indicator of a miscarriage, varying in intensity from light spotting to heavy discharge. In some instances, the body naturally expels the pregnancy tissue without the need for medical intervention, a practice known as expectant management, commonly employed for early miscarriages.


In situations where the miscarriage is incomplete or presents complications, a healthcare provider may recommend medication to facilitate the expulsion of the remaining tissue. Alternatively, a surgical procedure, such as dilation and curettage (D&C) or aspiration, may be necessary to remove the pregnancy tissue.


To help individuals and couples navigate the emotional impact of pregnancy loss, grief counseling and participation in support groups can provide valuable assistance.


An ectopic pregnancy occurs when the implantation of a zygote takes place outside of the uterus or in an abnormal location within the uterus (See Figure 2). In 95% of ectopic pregnancies occur in the fallopian tubes, but they can also occur in the abdomen or cervix. The pain may be characterized as unilateral or generalized, crampy or sharp. Vaginal bleeding and spotting can also occur. Certain individuals may also encounter nonspecific symptoms, such as an unusual urge to defecate, which can occasionally overlap with common pregnancy signs.


The risk of an ectopic pregnancy is elevated in cases of a previous ectopic pregnancy, a history of pelvic infection (e.g., chlamydia and gonorrhea), the use of an intrauterine device (IUD), the presence of endometriosis, or factors that impede ovum transport, including the use of oral contraceptive pills (OCP) or smoking.


HIV primarily targets immune system cells, particularly CD4+ T cells, leading to immune system impairment. In adults infected with HIV, a spectrum of symptoms may manifest, including flu-like indicators such as fever, fatigue, and swollen lymph nodes. If left untreated, HIV can progress to Acquired Immunodeficiency Syndrome (AIDS), resulting in more severe health issues.


HIV shares common modes of transmission with other STI organisms. It can be transmitted from an infected mother to her newborn during childbirth, through breastfeeding, or during pregnancy. Newborns who acquire the virus may exhibit symptoms like failure to thrive with difficulty gaining weight or growing at a normal rate, recurring infections, including respiratory infections, ear infections, and gastrointestinal issues, and developmental delays, both physical and cognitive.


HIV shares common modes of transmission with other STI organisms. It can be transmitted from an infected mother to her newborn during childbirth, through breastfeeding, or during pregnancy. Newborns who acquire the virus may exhibit symptoms like


Nevertheless, with appropriate medical care and precautions, HIV-infected individuals can still give birth to healthy babies. Key steps and interventions for ensuring a healthy pregnancy include:


By adhering to these guidelines and working closely with healthcare providers, HIV-positive pregnant people can significantly minimize the risk of HIV transmission from mother to baby, thereby ensuring the best possible outcome for both.


Symptoms of HSV include the formation of small vesicles and shallow ulcers on the cervix, urethra, and perineum. Those who have never been previously infected with HSV often experience more severe symptoms.


In cases where the HSV virus comes into contact with an individual’s eyes, it can lead to blindness. Additionally, individuals with HSV have a heightened risk of developing cervical cancer. Pregnant women with HSV must exercise caution, as exposure of the fetus to HSV during birth can result in blindness or brain damage for the baby.


While it is possible to manage HSV to reduce the frequency and duration of outbreaks, it is not completely curable.


HPV, a DNA virus belonging to the Papillomaviridae family, encompasses over 200 distinct types. Approximately 40 of these variants are recognized for their ability to infect the genital region, giving rise to a variety of clinical conditions. The majority of HPV infections manifest without symptoms. However, certain HPV strains can instigate the formation of genital, anal, or surrounding warts, characterized by their raised, flat, or cauliflower-like appearance. Notably, high-risk HPV types have the potential to induce abnormal cell changes in the cervix, and in some instances, these changes may progress to cervical cancer. The administration of the HPV vaccine, such as Gardasil, can effectively thwart infection by some of the most dangeroud HPV types, subsequently reducing the risk of cervical cancer.


Much like other sexually transmitted infections (STIs), HPV is primarily transmitted through sexual contact and bodily secretions. Additionally, this virus can be passed from an infected mother to her newborn during the process of childbirth. Infants exposed to HPV during delivery may be susceptible to recurrent respiratory papillomatosis, a condition marked by the growth of warts in the airway, leading to respiratory difficulties.


While there is no cure for the HPV virus itself, HPV warts can be effectively managed through a range of treatment options. These include topical treatments in the form of creams, cryotherapy (which involves freezing the warts with liquid nitrogen), electrocautery (a method of burning off warts using an electrical current), and surgical removal by cutting out the affected warts. Regular monitoring and treatment are essential, often facilitated through pap smears conducted to detect abnormalities.


Gonorrhea is an STD that is caused by a sexually transmitted bacterium. The bacterium specifically associated with gonorrhea is known as Neisseria gonorrhoeae. This bacterium is mainly spread via sexual contact such as vaginal, anal, or oral sex. The bacterium can infect the vagina, urethra, paraurethral glands, and Bartholin glands, causing purulent inflammation of each.


In females, Neisseria gonorrhoeae can ascend to the cervix, uterine canal, and fallopian tubes, potentially causing inflammation and pain. In males, it can spread to the prostate and testis, leading to similar symptoms. Moreover, the bacterium can disseminate to other parts of the body, including the eyes, throat, rectum, and joints, causing inflammation even in these regions. Importantly, in many cases, there may be no symptoms associated with gonorrhea, although it is still transmissible.


Regardless of symptoms, treatment is highly recommended for all sexual partners involved to prevent further infection or complications. If left untreated, gonorrhea can lead to serious issues, such as pelvic inflammatory disease (PID) and infertility in women, as well as epididymitis and infertility in men. Additionally, it can be transmitted during childbirth, potentially causing neonatal conjunctival infection. Early detection and treatment are essential to mitigate the consequences of gonorrhea and reduce its spread.


Chlamydia is the most prevalent sexually transmitted infection (STD) caused by the bacterium Chlamydia trachomatis. It is a frequent culprit behind conditions like pelvic inflammatory disease (PID) and infertility, with many cases being asymptomatic.


Chlamydia tends to affect the urethra and cervix, often resulting in discharge. There is a notable link between Chlamydia infection and an increased risk of cervical cancer. Furthermore, individuals exposed to Chlamydia have a heightened susceptibility to contracting HIV.


During childbirth, Chlamydia can lead to neonatal lung and eye infections in the newborn. Due to these potential complications and the risk of transmission, it is strongly recommended that both partners receive treatment for Chlamydia. Early diagnosis and appropriate management are crucial for preventing adverse outcomes and reducing the spread of this common STD.


Syphilis, caused by the bacterium Treponema pallidum, is primarily transmitted through sexual contact. This complex disease presents several distinct stages and symptoms:


The good news is that syphilis is curable, especially when detected and treated early. Timely treatment with antibiotics can effectively eradicate the infection and prevent its progression to more severe stages.


Sexually transmitted diseases (STDs) can be transmitted through various means, including:


Correct and consistent use of latex condoms is an effective method for reducing the risk of STD transmission during sexual activity. Condoms provide a barrier that helps prevent direct contact with infected bodily fluids.  Therefore, it’s crucial to practice safe sex, get regular screenings, and seek prompt medical treatment when needed to prevent or manage the complications associated with STDs.


IVF is one of the most well-known ART methods. It involves the extraction of eggs from the ovaries, fertilizing them with sperm in a laboratory dish, and then transferring the resulting embryos into the uterus. IVF can be used for various fertility issues, including blocked fallopian tubes, male factor infertility, or unexplained infertility.


After IVF, excess embryos can be frozen (cryopreserved) for future use, allowing multiple attempts at pregnancy without repeating the ovarian stimulation and egg retrieval process.


ICSI is a specialized form of IVF where a single sperm is injected directly into an egg to facilitate fertilization. This method is particularly effective in cases of severe male factor infertility or when prior IVF attempts have not been successful.


GIFT is a technique in which eggs and sperm are collected and placed into the fallopian tubes, allowing fertilization to occur inside the woman’s body. It is less commonly used today due to the popularity of IVF.


ZIFT is similar to GIFT, but it involves the transfer of fertilized embryos (zygotes) into the fallopian tubes. This procedure is also less common than IVF.


IUI involves placing washed and concentrated sperm directly into the uterus, bypassing the cervix. It is often used for mild male factor infertility or when the cervix is a barrier to conception.


Donor sperm or eggs can be used when one partner is unable to provide viable gametes. This is often employed in cases of severe male or female infertility.


PGT involves testing embryos for genetic abnormalities before transferring them into the uterus. It can help reduce the risk of passing on certain genetic conditions.


In gestational surrogacy, another woman carries and gives birth to a baby for the intended parents, often using ART to achieve pregnancy. Traditional surrogacy involves the surrogate providing both the egg and carrying the pregnancy.


Assisted reproductive technologies have revolutionized the field of fertility treatment, offering hope to individuals and couples facing infertility. They are complex, highly regulated, and require the expertise of fertility specialists to ensure safe and successful outcomes. However, the cost of assisted reproductive technologies (ART) is very expensive and can vary significantly depending on the specific procedures, geographic location, and individual circumstances.


The treatment approach for female factor infertility is also tailored to the specific causes or etiologies identified. Some common treatment options for female factor infertility includes:


On the other hand, monitoring the common causes of anovulation can also be detected through physical examination and clinical assessment.


It’s important to consider that approximately 20-30% of cases can be attributed to pelvic abnormalities, such as tubal occlusion, adhesions, and severe endometriosis.


One diagnostic approach to rule out tubal factor infertility is the use of a Hysterosalpingogram (HSG). This diagnostic test should ideally be conducted relatively early in the infertility investigation, following a semen analysis.


Hysterosalpingogram (HSG) is typically performed in the follicular phase of the menstrual cycle before ovulation. In cases where the HSG results are inconclusive or further investigation is warranted, laparoscopy may be recommended.


Laparoscopy is a surgical procedure that allows for a direct visual examination of the pelvic organs. It can provide a more detailed assessment of pelvic abnormalities, including the condition of the fallopian tubes, adhesions, and endometriosis.  Diagnostic laparoscopy involves the insertion of a fiberoptic scope through small incisions into the abdominal cavity, and is typically performed under general anesthesia.


During a diagnostic laparoscopy procedure, here’s what you can generally expect:


An endometrial biopsy can be used to assess endometrial factors. In the context of evaluating female infertility, it is crucial to consider the quality of the endometrium, which must be suitable to facilitate implantation. If it is not, this condition is referred to as luteal phase inadequacy (LPI). The assessment of endometrial factors involves:


When assessing cervical factor infertility, a sample of cervical mucus is typically collected at midcycle, which is the time of ovulation. The evaluation involves the following steps:


The assessment of cervical mucus quality plays a significant role in fertility evaluation, as it affects sperm transport and survival within the female reproductive tract. Healthy cervical mucus provides an environment that supports sperm motility and facilitates the journey of sperm to meet the egg for fertilization.


Semen analysis is typically the initial diagnostic step when assessing infertile couples and excluding male infertility factors. This test provides crucial insights into the quality and quantity of sperm present in the semen.


Semen samples can be collected either at a laboratory or at home. If collected at home, the sample should be transported to the laboratory within 30 minutes to ensure accurate results. Men are advised to abstain from ejaculation for 48 to 72 hours before collecting the semen sample to ensure that the sample contains an adequate concentration of sperm.


The first milliliter of the ejaculate typically contains the highest concentration of spermatozoa, so it’s important to include this portion in the sample. To account for natural variability in semen quality, at least two specimens should be examined on different occasions, several weeks apart. Parameters analyzed are as follows:


Antisperm antibodies are antibodies that target sperm cells. They can be present in either the male or female partner and may contribute to fertility impairment. These antibodies can interfere with sperm function and motility, making it difficult for sperm to reach and fertilize the egg. Assays to detect the presence of anti-sperm antibodies, semen, blood, and vaginal fluids that fight off sperms help identify this potential factor in infertility.


The HEPT is a laboratory test used to predict the fertilizing capability of spermatozoa. It involves exposing sperm to hamster eggs and observing their ability to penetrate the egg’s membrane. This test provides insights into whether sperm can successfully penetrate the egg, which might not be evident through a standard semen analysis. It evaluates factors related to the interaction between sperm and the egg’s outer layer.


Sperm DNA fragmentation assays assess the integrity of sperm DNA. High levels of DNA fragmentation can indicate damaged genetic material within sperm cells. This damage could impact the development of normal embryos and lead to fertility issues. These assays help predict the likelihood of successful embryo development.


PCT provides insights into the interaction between sperm and cervical mucus, which is important for transporting sperm through the reproductive tract. The test should not replace a comprehensive semen analysis but serve as a supplemental assessment to evaluate specific aspects of fertility.


The PCT is typically performed during the midcycle, the period in which there is high water content in cervical mucus and the midcycle estrogen surges. This timing is chosen because cervical mucus plays a crucial role in facilitating sperm transport. The couple should engage in sexual intercourse between 8 to 24 hours prior to presenting at the clinic for the test.


PCT examines cervical mucus under a microscope to determine the presence of several progressively motile spermatozoa per high-powered field. This assessment helps evaluate sperm’s ability to move effectively in the cervical environment. It can screen for the presence of anti-sperm antibodies and the adequacy of the couple’s sexual activity. For example, the presence of clumpy sperm or flagellate without motility might indicate the presence of anti-sperm antibodies originating from either mucus or semen. In cases where few or no sperm are detected, potential factors to consider include improper timing of the test, oligospermia (low sperm count), suboptimal coital technique, hypospadias, the presence of anti-sperm antibodies, or the presence of naturally occurring hostile cervical mucus.


In couples who are trying to conceive naturally, approximately 50% of them achieve pregnancy after trying for about three months. However, the chances of conception increase with time, and by the end of 12 months, about 92% of couples will have successfully conceived.


Answering these questions can help gauge the characteristics of a menstrual cycle and provide insights into whether it falls within the typical or atypical range. If any concerns or irregularities are identified, it’s advisable to consult with a healthcare professional for further evaluation and guidance.


The concept behind these vaccines is to suppress sperm production and reduce the likelihood of fertilization. Hormonal vaccines for male contraception are still in the experimental and clinical trial stages, and their effectiveness, safety, and long-term implications are actively being studied. If successfully developed and approved, they would offer men an additional option for family planning and contraception.


However, it is important to note that as of 2023, no hormonal vaccine for male contraception has been widely approved for public use. Progress in this field may have occurred since that time, so it’s advisable to check the latest developments and consult healthcare professionals for the most up-to-date information on male contraception options.


Fertility awareness is another method used to support postpartum contraception, but it may be difficult to practice until regular cycles are reestablished. Barrier methods such as the diaphragm and cervical cap are good contraception methods for lactating women but should be refit at six weeks postpartum. An IUD can be placed immediately postpartum but is normally placed 6-8 weeks postpartum or sterilization.


Combined birth control pills are not good options for lactating women as estrogen decreases milk supply but can be taken after three months. Women who are not breastfeeding should wait to start taking combination birth control pills until 2-3 weeks postpartum due to the risk of thromboembolism.


Emergency contraception methods are used after intercourse to prevent pregnancy. For emergency contraception to be effective, it has to be used within 72 hours of unprotected intercourse taking place, but effectiveness is greater the sooner the contraceptive method is used. It may decrease the chance of pregnancy by 75%. Emergency contraception can be used for up to 5 days after intercourse with some efficacy but not as effective as taking it within the first 72 hours.


The morning-after pill is intended for use following unprotected intercourse during the ovulation period. It contains a substantial dosage of steroids, which serves to disrupt the endometrial lining after ovulation has taken place, preventing the implantation of a fertilized egg.


Plan B is an emergency contraception available “behind the counter,” without a prescription, for those 18 years of age or older. If you are under 18 years old, you require a prescription to take Plan B. Levonorgestrel are two 0.75 mg pills that can be taken together or taken 12 hours apart for five days.


Preven is a product with ethinyl estradiol and levonorgestrel, approved for emergency contraception. The side effects of emergency contraceptives include nausea, abdominal pain, fatigue, headache, bleeding irregularities, breast tenderness, diarrhea, and vomiting.


This method of contraception is not as effective as other methods of contraception. A pregnancy test should be used if there is any delay in the menstruation cycle. If pregnancy occurs, therapeutic abortion is recommended as it has a teratogenic effect.


Paraguard is another form of emergency contraception that can be inserted within five days of unprotected intercourse.


Surgical sterilization is permanent, effective, and has no side effects. The mortality rate of the procedure is 1-2/100,000. The risk of ectopic pregnancy is elevated at 33%, a notable increase compared to the 1.5% risk seen in the general population.


Regret occurs more often for younger patients or during postpartum when the patient’s life situation changes. Tubal reversals are only successful in 43-80% of cases and are expensive. If a patient wishes to conceive after tubal ligation, in vitro fertilization is a successful option but can be very expensive.


Surgical sterilization in men is accomplished through a procedure known as vasectomy. Vasectomy is recognized for its superior safety, cost-effectiveness, and efficacy when compared to female sterilization. In the United States, approximately 4.2 million men opt for vasectomy as their sterilization method of choice. The one-year failure rate for vasectomy stands impressively low at 0.15%, in contrast to the 0.5% failure rate associated with female sterilization. Additionally, male sterilization costs roughly one-third of the expenses incurred with bilateral tubal ligation. Vasectomies are routinely performed in an office setting under local anesthesia. To confirm the success of the procedure, two negative semen analyses are typically required.


The advantages of intrauterine devices include the ability to return to fertility after removal and are also an option for women who are unable to take estrogen. They also lack systemic side effects, have immediate high efficacy, single motivational act, and lack interference with lactation.


The disadvantages of an IUD are they can lead to a slight increase risk of infection during the month following insertion, an increase in menstrual bleeding and cramps, and expulsion and perforation of the uterine fundus.


Pregnancies can occur with the IUD in place, which causes a 55% risk of spontaneous abortion. IUDs also lead to a higher chance of having an ectopic pregnancy. Prematurity is also a risk of about 12-15% while the IUD is in situ.


Contraindications to intrauterine devices include various conditions related to pregnancy, pelvic inflammatory disease, and the uterus. You are to be cautious when using an IUD if you are suspected of being pregnant or known to be and should have it removed. You should also be cautious if you have had a previous ectopic pregnancy. You should also be wary of using an IUD if you are at high risk for pelvic inflammatory disease or a partner that has multiple sexual partners. Other conditions include untreated acute cervicitis or vaginitis, conditions that have increased susceptibility to infections, postpartum or postabortal endometritis in the past 3 months, undiagnosed abnormal genital bleeding, distorted uterine cavity from leiomyomata, uterine anomalies or known or suspected cervical or uterine malignancy, including an unresolved abnormal Pap smear.


A contraceptive vaginal ring (Nuvaring) is an intravaginal ring that releases continuous progestin and estrogen. They are changed monthly with three weeks of ring use and one week off. The hormones that are released from the contraceptive vaginal ring are absorbed through the vaginal epithelium.


Progestin administration works by inhibiting ovulation, thickening the cervical mucous, and causing atrophy of the endometrial lining. Progestin can be administered in oral, injectable, or subdermal implants on a continuous basis. Women have to be compulsive for the maximum efficiency as there is no pill-free interval. The implantable or injectable forms are effective and lack the requirement of responsibility.


Progestin administration is less effective and is associated with more breakthrough bleeding than the combination of estrogen and progestin. It does have fewer serious side effects, as progestin does not promote clotting, which would not cause a risk of heart attacks or stroke regardless of age or smoking status. Progestin administration also lowers HDL but has not been shown to contribute clinically to heart disease. Although there are fewer serious side effects, the FDA requires the same thrombosis precautions on all hormonal contraceptives.


Depo-Provera is 150 mg of a medroxyprogesterone acetate in a sustained release suspension that is administered every three months. This method is extremely effective, with a failure rate of 0.3% during the first year of use. Ammenorrhea is experienced in 50% of women who use depo-provera after one year of use. The most common side effects are irregular bleeding and an increase in weight. When depo-provera is no longer being used, the average return to fertility is 9-10 months.


Implanon is a subdermal implant that is a single rod that releases etonogestrel. Implanon is very effective for three years. The mechanisms of action in this subdermal implant are very similar to the other progestin-only methods. The most common reason for discontinuation of the implant is irregular bleeding.


The most common side effect of OCP is breakthrough bleeding, bleeding outside of the menstrual cycle caused by estrogen and progesterone deficiency or missing pills. Side effects caused by excess estrogen may include nausea, water retention, and vascular headaches. Side effects caused by excess progestin may include an increase in appetite and weight gain, acne, depression, and pill amenorrhea. Newer anti-androgenic progestins may experience a decrease in libido. Most women experience mild to no side effects with low-dose formulations of less than 50 micrograms of ethinyl estradiol.


Complications of OCP may include cardiovascular complications, neoplasia or post-pill ammenorrhea. Cardiovascular complications include myocardial infarction, cerebrovascular accident, or thromboembolism. Cardiovascular complications take place in women over 35 who smoke and in some women who have underlying medical problems, particularly with conditions predisposing to thrombosis. Neoplasia can take place in the breast, cervix, endometrium, and ovary. Post-pill amenorrhea occurs in up to 3% of women who discontinue OCP.


Contraindications to oral contraceptives related to estrogen components include various conditions related to the heart, liver, lungs, and cancer. Individuals should be cautious when taking oral contraceptives if they have thromboembolic disorder, cerebrovascular accident, coronary artery disease, impaired liver function, hepatic adenoma, breast cancer, endometrial cancer, other estrogen-dependent malignancies, pregnancy, undiagnosed vaginal bleeding, or if they smoke more than 15 cigarettes per day over the age of 35. Taking oral contraceptives with these conditions can lead to further damage or more risks.


Male condoms are safe, effective, inexpensive, and have reversible effects. Male condoms that successfully prevent pregnancy are manufactured using latex, lamb caecum, or polyurethane. For patients with latex allergies, polyurethane condoms are a good alternative. Latex condoms should only be used with water-based lubricants (KY jelly, spermicidal agents). Oil-based lubricants such as lotion, petroleum jelly, or massage oil may damage the condom. Male condoms prevent pregnancy and protect from STDs (cervical cancer). In the first year, failure rates with condom use are 3% with perfect use.[1] Failures occur more frequently when condoms are not used than when condoms are used with malfunctions such as slippage or breakage.


Female condoms are loose plastic pouches that line the vagina, with the inner end covering the cervix and the outer end covering the labia. Female condoms should also be used with spermicides. They can be inserted 8 hours before intercourse and should be removed after coitus before the female stands up. The failure rate of female condoms is between 5-20%. The use of female condoms lowers the transmission of STDs.


The female diaphragm contraceptive is made of latex and has a dome shape. When using the diaphragm, it rests between the posterior aspect of the symphysis pubis and the posterior fornix of the vagina, covering the anterior vaginal wall and the cervix. It prevents sperm penetration into the cervical canal and cervical mucous from neutralizing vaginal acidity, which is hostile to sperm.


Female diaphragms should also be used with spermicidal cream. When using a diaphragm, it is best to use the largest comfortable size. It should be placed up to 6 hours before intercourse and left in place for 6 hours after intercourse. It should be worn for no more than 24 hours total. The diaphragm has a 20% failure rate with typical use. The diaphragm has a 6% failure rate over the first year with perfect use. The effects are reversible and have few side effects, such as urinary tract infections, but do not protect against STDs.


Cervical caps have the same effectiveness as the diaphragm but are harder to fit because they are held by suction. Cervical caps must be left in place for at least 6 hours after intercourse and used with spermicides. They can be left in place for 36 hours total. The cervical cap has a 20% failure rate with typical use. The cervical cap has a 6% failure rate over the first year with perfect use.


Vaginal sponges are used with polyurethane and nonoxynol 9. They release spermicides during coitus, absorb sperm, and block the entrance of the cervix canal. They can be inserted up to 24 hours before intercourse but must be removed after 30 hours. The failure rate of vaginal sponges is 10-15%.


Spermicides contain a gel, foam, cream, film, suppository base, and an active chemical agent such as nonoxynol-9. Spermicides can be used alone, with the diaphragm or cervical cap. The failure rate is 5-25% within the first year of use. Spermicide must be used at least 15 minutes before intercourse to allow it to adequately disperse. They are accessible, easy to use, safe, and enhance the efficiency of other forms of contraception. Decrease the risk of STDs by approximately 25%. Spermicides are not good options for patients who are allergic to any spermicide component or if the vaginal anatomy is abnormal.


Natural family planning is used in many ways, mostly by being aware of fertile times called fertility awareness methods. Abstaining from intercourse during fertile times can be calculated by tracking cycles and the lifespan of the ovum and sperm. For example, knowing that near ovulation, cervical secretion increases and becomes clear and stretchy and the cervix becomes softer and wider. After ovulation, basal body temperature increases due to progesterone.


During the first year, the failure rate of natural family planning methods is 25%, with only a 1-9% of failure rate with perfect use. Most couples use instructors initially to help interpret their fertility signs. Fertility signs are more difficult to interpret in those who have recently been on hormonal contraception, are near menarche or menopause, or who are just postpartum or post-breastfeeding.


Coitus interruptus is the withdrawal method, when the male withdrawals the penis before ejaculation. This is the primary means of contraception in at least 2% of couples in the United States. The failure rate is 4% during the first year, with a 19% failure rate with typical use. This method has no cost and no side effects. This method requires high motivation and does not protect from STDs.


A preterm labor is when labor occurs between week 20 and week 37 of pregnancy. There are several indications of preterm labor, including a multiple gestation pregnancy, a short cervix, a history of preterm labor, and drug use during pregnancy. A preterm labor can pose several risks to both mother and baby. These risks include a premature birth of a baby resulting in low birth weight, respiratory issues, immature organs, and vision issues. A premature birth also puts the baby at a higher risk of having cerebral palsy, learning disorders, and behavioral issues. In the worst cases, a premature death can mean the death of a baby. To avoid preterm labor, it is important that the mother regularly visits their doctor, does not use drugs, and gives ample time between pregnancies. There are also several ways to stop preterm labor from occurring, including medication and manually closing the cervical opening so nothing can pass through; however, these methods may or may not work.


There are several fetal positions that are considered abnormal and deemed a complication during labor and birth. These positions include fetal dystocia, breech, occiput posterior, shoulder dystocia, umbilical cord prolapse, and fetal distress. Fetal dystocia is when the fetus is smaller or larger than normal or in an abnormal position. This can lead to the umbilical cord being compressed. Breech position encapsulates complete, incomplete, frank, or footling breech. A complete breech is when the baby’s feet are closest to the birth canal and the knees are bent. An incomplete breech is when one of the baby’s knees is bent and close to the birth canal. A frank breech is when the baby’s legs are folded up near their face, and their bottom is nearest the birth canal. A footling breech is when the baby’s feet are closest to the birth canal and delivered first. Occiput posterior positioning is the most common abnormal fetal positioning and is when the occipital bone of the fetus is touching the mother’s sacrum.


Shoulder dystocia is when the head of the baby has exited the birth canal, but the shoulders get stuck. In this case, an episiotomy is an option to get the baby free. This positioning can result in injury such as fracture, brachial plexus, or brain injury to the baby if forced through. Another abnormal position is umbilical cord prolapse, which is when the umbilical cord comes through the birth canal before the fetus. Umbilical cord prolapse is a dangerous position, and a little under 10 percent of cases lead to fetal death. Lastly, fetal distress is when there is an irregular heartbeat coming from the baby. This is common in pregnancies at or past 42 weeks.


Preeclampsia is a special name for a case where a mother has high blood pressure during pregnancy. For women with initially normal blood pressure, preeclampsia usually presents around 20 weeks or more into the pregnancy. It is important for a mother and her doctor to keep on the lookout for signs of preeclampsia, including high blood pressure, excess protein in the urine, and edema in the legs. Preeclampsia is a pregnancy risk for both mother and baby, so if it does occur, it is important that the mother get oral or intravenous medication to stabilize the baby for birth. Often, a mother will need to consider the risk versus the reward of delivering early or going to term.


A miscarriage is when a woman’s pregnancy terminates before 20 weeks. Miscarriages are the most common way to lose a pregnancy, with 10 to 20 percent of pregnancies resulting in miscarriage. Miscarriage usually occurs due to poor or irregular development of the fetus or due to the age and health of the mother. High fetal cortisol levels can also increase the chances of a miscarriage occurring. Although there are medications to lessen complications of a miscarriage, there are no known ways to stop a miscarriage once it has been initiated. There are several ways to indicate that a miscarriage may be imminent, including the passage of fluid, blood, or tissue out of the vagina, abdominal pain, or lower back pain. Miscarriages are one of the most physically and emotionally distressing processes for a mother to endure.


A still birth is when there is fetal death inside the mother following 20 weeks of pregnancy. Usually, a still birth happens some time before labor, but sometimes it can occur during labor. Although still births are not quite as common as miscarriages, they do occur in approximately 1 out of 175 labors.[1] Several factors that can increase the chance of a still birth pregnancy are obesity, high blood pressure, diabetes, and drug use. However, still births can also occur in women without any of these risk factors. Once a still birth is found, it is critical it is removed to prevent any further complication or infection. There are several ways to remove the fetus, depending on how far along the pregnancy is. Some removal methods include cervical dilation and evacuation, induction of labor, and c-section.


Hemorrhaging can be a major issue related to labor and birth since a mother can have complications, including shock if they lose too much blood. During a normal vaginal birth, the mother typically loses around 500 mL of blood. During a c-section birth, a mother usually loses around 1000 mL of blood. Any more blood loss than this is considered excessive hemorrhaging. Most of this bleeding occurs after the placenta has been delivered. Certain situations put a mother at higher risk for excessive hemorrhage, including placental abruption, prolonged labor, assisted delivery, infection, blood clotting disorders, and obesity.


Labor and birth can result in vaginal or anal tearing. The risk of tearing is increased in situations such as rapid labor or an abnormally large baby. There are also several different degrees of tearing. A first-degree tear is when the skin between the vagina and rectum tears. A second-degree tear is when there is a tearing of the perineal muscles. A third-degree is when there is a tearing of the perineal muscles and anal sphincter. Finally, a fourth-degree tear is when there is a tearing of the mucous membrane lining the rectum. Tearing can cause several issues for the mother, including fecal incontinence and dyspareunia.


In conclusion, labor and birth can vary from one situation to another. There are multiple signs of impending labor, and there are also false signs of labor. Labor has several different stages and involves the birthing of both the baby and the placenta. The birthing process has several different forms, including natural and cesarean births. During labor and the birthing process, there are several medications and tools that can be used to help reduce pain and ease the process along more smoothly. Lastly, labor and birth are often somewhat long and strenuous processes with many different variables that can lead to complications.


The epidural will become effective approximately 10 to 20 minutes following administration and is long-lasting to provide pain relief throughout labor. The composition of an epidural is a combination of anesthetics and opioids such as bupivacaine, ropivacaine, and fentanyl. There are several additional risks that come with using an epidural. These risks include increased difficulty in pushing, lowered blood pressure, halted labor, and difficulty walking due to numbness.


Another method that can be used for pain relief during labor is by administering intravenous pain medication. This method is often used when the mother is unable to do a spinal block or epidural. One of the downsides of intravenous pain medication is that it can cause drowsiness in the mother and baby. Once a mother reaches the stage of labor where they are pushing, they have the option for a pudendal block. This block reduces feeling in the birth canal and is often combined with other pain relief methods. A pudendal block is commonly composed of lidocaine or chloroprocaine.


Rupture of Membranes is the technical phrase for saying that a mother’s water has broken. The phrase “water has broken” means that the amniotic sac has ruptured, releasing fluid and indicating that labor is imminent. Not all women experience this the same. Some experience a burst of water, and others have a slow stream or trickle. Once a mother’s water has broken, it is important that she immediately go to the hospital to minimize the risk of infection.


The cervix undergoes several changes to get ready for delivery through the birthing canal. These changes include ripening, effacement, and dilation. Ripening is cervical softening, effacement is cervical thinning, and dilation is cervical opening. Dilation is a term commonly heard throughout pregnancy as the doctor measures the amount of dilation to the cervix over time until full dilation has been reached and it is time to deliver.


There are several additional signs of labor. For instance, vaginal discharge tends to thicken as labor nears. This is due to the mucous plug from the cervix getting displaced into the vaginal canal, and is often an indication that the cervix is starting to dilate. Sometimes, there is some blood in this discharge, which is common. Another sign of labor is nesting, a set of behaviors from the mother that involve an excess need to organize, clean, and prepare everything before the baby arrives. Additionally, a slight drop in weight can signal labor.


There are several hormones involved in the onset of labor. Here, we will go through each of the hormones and what purpose they serve. Corticoptropin-Releasing Hormone (CHR) is a hormone released from the hypothalamus during labor stress that supports the development of the hormone Corticotropin (ACTH). ACTH is produced by the pituitary gland, and stimulates cortisol production by the adrenal glands, which leads to the release of estrogen that prepares the mother for childbirth. DHEA-sulfate, which is a steroid, comes into play in the last stage of pregnancy as an estrogen substrate.


Other more common hormones that come into play in preparation for labor are estrogen, progesterone, and prostaglandins. Estrogen is produced by the ovaries and fetal placenta. It helps to soften the cervix in preparation for dilation, and is involved in the manufacture of prostaglandins that participate in uterine muscle contraction. Progesterone is produced by the placenta and inhibits uterine contractions. A significant drop in progesterone during pregnancy is what initiates labor at the placental site by no longer inhibiting uterine contractions.


The ratio of estrogen to progesterone is important during labor. Prostaglandins are produced by tissue cells, and their main function is to help promote labor by stimulating the uterus muscle to contract. Fetal cortisol levels are also important, as they stimulate the production of enzymes that help regulate the development of placental alternatives, such as the lungs and liver, after birth.[1]


of estrogen to progesterone is important during labor. Prostaglandins are produced by tissue cells, and their main function is to help promote labor by stimulating the uterus muscle to contract. Fetal cortisol levels are also important, as they stimulate the production of enzymes that help regulate the development of placental alternatives, such as the lungs and liver, after birth.[1]


Lastly, oxytocin is a hormone produced by the pituitary gland and placenta. Oxytocin release helps stimulate the contraction of the uterine muscles and increase prostaglandin release to further increase contractions and dilate the cervix. There are oxytocin receptors located in both the myometrium and parietal decidua of the uterus. There are several different types of oxytocin that play a role in labor: placental, pituitary, and synthetic. Labor initiation is assisted by placental oxytocin. Contractions and prostaglandin release are further coaxed by a physician when they administer synthetic oxytocin. Upon every contraction, pituitary oxytocin is released and assists in decreasing pain, anxiety, and stress in the person going through labor. In fact, this form of oxytocin stimulates the parasympathetic nervous system to offset the sympathetic nervous system during labor. Pituitary oxytocin also increases activity in the reward centers of the brain which produces feelings of pleasure.[2]


The first stage of labor is the longest, lasting approximately 20 hours for individuals who are giving birth for the first time and less than 14 hours for those who have given birth before. The first stage of labor is composed of two different phases: latent and active.


During the latent phase, the cervix dilates from 0 to 6 cm. During the active phase, the cervix dilates from 6 to 10 cm (full dilation). If there is a halt to cervical change or contractions after 4 or 6 hours respectively, this is a sign of labor complications.


The second stage of labor involves the process of the fetus exiting through the birthing canal. This stage can last approximately 2 hours for those who are giving birth for the first time or up to 30 minutes for those who have given birth before. During this stage, contractions typically last for 1 minute with 2 to 3 minute periods of relaxation in between. The baby will start to “crown” during this stage, with the head approaching the exterior of the birthing canal. Since the skull bones of the baby are not fused, their head may appear cone-shaped. In a normal birth, the baby’s head will be delivered first, followed by its shoulders. Once the shoulders pass through, the rest of the body should deliver easily as the shoulders are the widest part to pass through the birthing canal. Once the baby has been delivered, it will take its first breath or be stimulated to cry and take its first breath. In an uncomplicated delivery, the umbilical cord will be cut within minutes of delivery. If the delivery had complications, there will be a further assessment on whether or not to cut the umbilical cord right away.


The third and final stage of labor involves the delivery of the placenta. This process usually takes no longer than 30 minutes to complete. If it takes longer than 30 minutes, there is an increased risk of hemorrhage. During this stage, oxytocin is still at work stimulating contractions of the uterus to get the placenta to detach and exit the birthing canal. There are several signs that the placental birthing process has started, and these include the elongation of the umbilical cord, fundus position, and a short increase in blood flow from vagina. Once the placenta has been birthed, there are several options for how it might be used. For example, the hemopoietic cells of the placenta might be used in cancer patients. It can also be frozen and used if the baby falls ill later on.


A natural birth is a birth through the vagina with no additional medical procedures. Natural birth can occur with or without medicine. Without medicine, breathing and relaxation techniques can be used to relax the mother as much as possible during labor. Medicine can also be used during a natural birth, such as an epidural, to reduce pain for the mother. There are several risks associated with a natural birth, which include but are not limited to tearing, infection, and loss of blood. There are additional risks in labor when an epidural is used, including infection, nerve damage, and seizures.


An alternative to a natural birth is a cesarean birth (or c-section), which involves medical intervention via abdominal and uterine surgery to remove the baby from the womb. There are several reasons why a cesarean birth may be performed instead of a natural birth, including but not limited to unprogressive labor, baby in distress, abnormal baby positioning, multiple gestation birth, umbilical cord prolapse, placental issues, a previous c-section, or health concerns. Cesarean birth is a surgical procedure and it does have some more risk associated with it than a natural birth. This risk includes infection, clotting, blood loss (hemorrhage), and associated surgical injuries. However, cesarean births are not uncommon. In fact, in 2021, there were 1,174,545 deliveries via c-section and 2,486,856 deliveries via natural birth.[3]


Those who are pregnant should make sure to have at least one general dental care appointment, and they are not restricted from getting any specific dental work done. Immunizations are allowed and getting or maintaining regular vaccinations is encouraged as long as they are not live virus vaccines. When it comes to traveling, there are no restrictions; however, the pregnant person will need to stretch and walk around every two hours.


Medication must be taken with care during pregnancy. The fetus will be exposed to anything that the mother consumes. In the case of medication, it is important to discuss different risks associated with medications and whether the reward is worth the risk. There is one specific medicine that should be avoided during pregnancy: aspirin. This is because ingesting aspirin can push back the time of labor, restrict the growth of the fetus, separate the placenta from the uterine wall, and remove bilirubin from protein binding sites.


For a pregnant individual to ensure that they and their baby are healthy throughout pregnancy, it is important that they maintain regular doctor appointments. From conception up until 32 weeks, it is recommended that the pregnant person have a doctor’s visit once a month. From 32 to 36 weeks, they are recommended to have a doctor’s appointment every other week. Finally, from 36 weeks until the birth of the child, the pregnant person is expected to have a doctor’s appointment once a week. At these appointments, the doctor will check for multiple things including contractions of the uterus, heart rate and movement of the fetus, amniotic fluid volume discrepancies, and bleeding from the vagina.


When it comes to calories, pregnant women need to increase their daily caloric intake by about 15%, which means that weight loss programs are not an option during pregnancy. As for protein, the pregnant person should intakes 1.3 mg more per day than usual.


Another change to the hematologic system includes an increase in factors that help with coagulation. A fibrin degradation inhibitor is also synthesized by the placenta. All of these changes to the hematologic system contribute to pregnancy being in a state of hypercoagulability, making pregnant women more prone to thromboembolic disease.


Several changes to the renal system occur during pregnancy as well. For instance, the glomerular filtration rate (GFR) and renal plasma flow (RPF) rise by 50 and 75 percent, respectively. The amount of plasma filtered of creatinine per unit time also rises. The kidneys themselves also get larger and, in turn, weigh more. The ureters, which connect the kidneys to the bladder, also enlarge, making their central cavity wider than normal. The bladder, which usually resides in the pelvis, becomes situated in the abdomen. Due to all these changes in the renal system, it is more common for pregnant people to have to urinate more often and sometimes not have total control over urination. Pregnant individuals are also more prone to kidney infection, and, if they are involved in a traumatic incident affecting the abdomen, a ruptured bladder will often be observed.


During pregnancy, the levels of progesterone are increased, impacting the movement of waste through the GI system. This can lead to constipation. Increased progesterone can also cause nausea and vomiting during the early stages of pregnancy, and in more severe cases may lead to hyperemesis gravidarum. It is also common for pregnant women to feel as if they are not hungry even though they have not eaten for a while. Due to the stomach and esophagus being pushed upon and moved by the enlargement of the uterus, many pregnant people will also experience heartburn during pregnancy.


Noticeable changes to the integumentary system, especially around the abdominal area, occur during pregnancy. As the uterus grows with the developing fetus, stress is put on the surrounding skin, often resulting in stretch marks. This is due to the collagen in the skin parting and can result in an itchy feeling in the affected area. The last 20 weeks of pregnancy are when women will start to see striae gravidarum on their stomach, which post-pregnancy will become striae albicans (stretch marks).


Hormones play a major role throughout pregnancy. Different hormonal levels and types are found in pregnant women compared to non-pregnant women.  Some of these hormones are newly found in the pregnant individual, or their levels may be varied compared to non-pregnant people. The sources of these hormones may come from the newly developed placenta, the fetus, or from the mother’s tissues.


The hormones that have been detected during pregnancy have been studied to distinguish between normal and abnormal pregnancies, detect fetal conditions, and identify any complications that may occur during pregnancy. Significant hormones present during pregnancy are listed below.


This hormone is produced by the syncytiotrophoblast of the placenta. HCG can be detected as early as six to eight days following conception and throughout the rest of the pregnancy.  It can be detected in blood first, and is later noticeable in urine. HCG has a specific pattern during pregnancy. Its levels rise rapidly 8 days after conception, doubling every two to three days and reaching its peak at 80 days after fertilization. Then it drops to a plateau for the remainder of the pregnancy.


HCG is used to detect both normal uterine and ectopic pregnancies. Its pattern and peak run at a much lower level in ectopic pregnancies than in normal pregnancies, and in conditions with poor placental function or fetal demise. HCG levels will be duplicated in multiple pregnancies with multiple placenta, and can reach very high levels in trophoblastic neoplasms. During pregnancy, HCG functions to prompt the corpus luteum to produce progesterone, and prompts male fetus’ Leydig cells to produce testosterone. HCG is similar to LH hormones and also helps induce ovulation.


Like HCG, this hormone is also produced by the syncytiotrophoblast of the placenta. hPL is formed as early as three weeks post conception and can be detected in a maternal bloodstream around six weeks post conception. hPL rises steadily in the first and second trimesters, and it disappears rapidly after delivery. hPL is a growth hormone, and its level correlates directly to the weight of the fetus and placenta. Very high maternal levels of hPL are often associated with multiple gestation, twins, or triplets.


The hPL has a significant effect on fetal development.  It favors protein synthesis and ensures a source of amino acids for fetal growth. It promotes the formation of insulin-like growth factors and induces the growth of all fetal tissues.


In the mother, hPl has a diabetogenic effect. It induces insulin resistance and carbohydrate intolerance, inhibiting glucose uptake in the mother. This can lead to the elevation of maternal blood sugar in those predisposed to high blood sugar.


Prolactin is a hormone produced by both the mother’s and fetus’s pituitary glands. It is also produced by the decidualized tissues of the maternal endometrium. Prolactin can be detected in maternal serum as well as maternal amniotic fluid. Maternal prolactin levels rise to a maximum of 100ng/ml near term.


Prolactin stimulates the production of milk by the mammary glands and prepares them for lactation after birth. The decidual prolactin secreted by the endometrium is thought to be important for electrolyte regulation of the amniotic fluids.


Higher levels of prolactin in a non-pregnant woman would indicate a hyperactive or tumor function of the pituitary gland.


AFP is a hormone produced by the yolk sac and liver of the fetus. It can be detected in the amniotic fluid at five to twelve weeks following conception and in the pregnant woman’s bloodstream around 15 to 17 weeks following conception. The exact role of alpha-fetoprotein remains a question, but it is known that it is mainly found in large amounts in the fetus’s central nervous system (CNS). Abnormal direct contact of fetal CNS with the amniotic fluid, as in neural tubal defect, results in elevated amniotic fluid and maternal blood levels of alpha-fetoprotein. In pregnancies involving a fetus with Down’s syndrome (DS), the level of alpha-fetoprotein measured in maternal serum and amniotic fluid is reduced to about 70 percent of the level attained in typical pregnancies.


Progesterone is produced by the corpus luteum follicle. In a non-conception cycle, progesterone is produced during ovulation at an amount of up to 25 mg per day. In the conception cycle, during the luteal phase, hCG stimulates more progesterone secretion by the corpus luteum and progesterone levels increase gradually and slowly. Progesterone continues to be produced by the corpus luteum until 7 to 10 weeks of gestation. Around 10 weeks post-conception, the placenta takes form and supplements the corpus luteum. Progesterone continues to be produced by the placenta until the delivery time. Its level is increased rapidly during pregnancy until the time of parturition up to -250mg/day. A very high level of progesterone could be indicative of multiple gestation.


Progesterone is required for decidualization and preparation of the endometrium for implantation. It also helps to maintain a relaxed myometrium until labor occurs. Interruption of progesterone levels or its action may lead to the termination of pregnancy.  Progesterone serves as a major precursor to critical fetal hormones during pregnancy. The fetal adrenal cortex glands uses placental progesterone as a precursor for corticosteroids, and fetus testes use placental progesterone as a precursor for testosterone.


The estrogen hormone is unique in that the mother, placenta, and fetus produce it. Estriol, the primary form of estrogen involved in pregnancy, is synthesized in the second trimester and is produced in increasing amounts until term. This surge in estriol is what causes the total amount of estrogen to increase 1,000 times more than that of a non-pregnant woman. Estrogen levels are indicative of both a fetus’s and placenta’s well-being. If the level of estrogen appears low or does not increase from the second trimester until term as expected, this may indicate pregnancy complications, fetal demise, or fetal growth retardation.


Obtaining and documenting a thorough genetic history alone is important. It can help narrow done and possibly rule out chances of a genetic order or birth defect. Health status and history of first-, second-, and third-degree relatives will be gathered. Any history of repetitive spontaneous miscarriage, stillbirths, and anomalous fetuses will be recorded. The ethnicities, ages, and any drug exposure of the mother and father will also be recorded.


Maternal serum alpha fetoprotein (MSAFP) levels can be tested at 15 to 17 weeks of gestation. A low level of MSAFP is indicative of an increased risk of trisomy in the fetus. A high level of MSAFP is indicative of a risk for open defects of the neural tube or GI tract.


Genetic amniocentesis is a procedure that involves puncturing the amniotic sac with a needle to gather a sample of fetal cells from the amniotic fluid. This procedure can be performed from 16 to 18 weeks of gestation via the withdrawal of about 30 mL of amniotic fluid. The fetal cells gathered can be used for fetal DNA analysis and fetal karyotype. A pregnant woman should be offered this option if she meets the following criteria: 35 years or older, history of multiple miscarriages, family history of genetic disease, or abnormal levels of MSAFP detected.


Amniocentesis is an invasive and high-risk procedure. It may lead to the leakage of amniotic fluid, spontaneous labor, or puncture of the fetus. The incidence of spontaneous abortion may result in approximately 1/200 to 1/400 of cases after amniocentesis.


Percutaneous umbilical cord blood sampling (PUBS) is a procedure involving an ultrasound-guided needle which is punctured into the fetal umbilical blood vessels to get a sample of fetal blood. This fetal blood sample can be used for fetal DNA analysis, fetal karyotype, fetal blood count, or assessment of the fetal acid base status. This procedure can be done at 18 weeks of gestation, but has a fairly high risk of fetal loss at 2-3%.


There are many different genetic disorders to look out for when it comes to pregnancy. It is very important for a pregnant woman or even a woman thinking of getting pregnant to get genetic counseling as well as prenatal diagnosis when necessary. This empowers the prospective parents to make informed decisions if a genetic disorder is identified, including whether to continue or terminate the pregnancy.


It is important to recognize that there are legal regulations in place governing an individual’s choice to terminate a pregnancy at different stages of gestation. During the first trimester, the decision to terminate lies entirely with the pregnant woman and her physician. During the second trimester, there may be state regulations imposed with respect to the mother’s health. During the third trimester, abortion may be regulated by the state unless the mother’s health is of concern.


These regulations highlight the significance of early diagnosis in pregnancy, allowing sufficient time for thoughtful decision-making, taking into account both medical and legal considerations.


Klinefelter syndrome is caused by the presence of an additional X sex chromosome. For instance, 47XXY. It is caused by maternal meiotic nondisjunction, the incidence of which increases with maternal age. There is no increased risk of reoccurrence: if it happens once, it is not likely to happen again. Rather, it is the same risk of occurrence as in the general population.


Klinefelter syndrome affects 1 in 1,000 newborn boys and is most often undiagnosed preceding puberty. Those with Klinefelter syndrome tend to be taller than average with incomplete musculature, enlarged breasts, small testis, decreased testosterone production, male infertility, and decreased motor skills and dexterity (Figure 1). However, those with Klinefelter Syndrome can usually be sexually active without much issue.


It results in improper development of the reproductive system, including degeneration of ovaries into fibrous streaks. It also results in a lack of development at puberty, minimal breast bud development, and is the most common cause of primary amenorrhea. Those with Turner’s syndrome often have short heights, a webbed neck, widely separated nipples, a malformation of the aorta, and excess fluid in the extremities resulting from malfunctioning of the lymphatic system.


A pseudohermaphrodite will have gonads matching that of their chromosomal sex. However, the external genitalia will not match that of their chromosomal sex. Rather, the external genitalia will match those of the opposite sex.


A male pseudohermaphrodite is an individual who possesses testes as their gonads but has external genitalia that appear female. This condition is often associated with disorders like Androgen Insensitivity Syndrome (AIS) and defective testosterone synthesis. AIS is a genetic condition in which the body is unable to respond to androgens (male sex hormones), resulting in incomplete masculinization of the external genitalia and the development of female secondary sexual characteristics. Defects in testosterone synthesis can further contribute to the feminization of external genitalia in individuals who have male gonads. These conditions highlight the complexity of sex development and the role of hormonal factors in determining an individual’s sexual characteristics.


A female pseudohermaphrodite is an individual with ovaries as their gonads, who has male external genitalia that have formed due to the fusion of the labia majora. This condition is often associated with an increase in androgen hormones. Female pseudohermaphrodites account for approximately 50% of all human intersexuality cases.


The development of a female pseudohermaphrodite is often attributed to hormonal influences during pregnancy, including the excess production of androgens, such as in the case of adrenal hyperplasia, or the administration of hormones like progesterone to the mother. These hormonal imbalances or exposures during fetal development can disrupt the typical differentiation of the external genitalia, leading to the formation of male-like genitalia in individuals with female gonads.


Developmental factors are associated with 10% of all birth defects. Developmental factors can be due to a teratogenic agent, infectious agent (e.g. rubella virus, herpes virus), or metabolic disorder (eg. diabetes, phenylketonuria). Teratogenic agent exposure is seen in less than 50% of all birth defect cases. Information important to teratogenic exposure defects includes the agent type, dose, length of exposure, and developmental stage at the time of exposure.


Genetic disorders are a much more common cause of abnormal fetal development and are associated with 20-25% of birth defects. In fact, 42% of spontaneously aborted fetuses are associated with a genetic disorder. Genetic disorders are also the cause of nearly 4000 different human diseases.


A genetic disorder is a medical condition caused by abnormalities in an individual’s DNA, which can result in various health problems. In a typical human, there are 22 pairs of autosomes (non-sex chromosomes) and 1 pair of sex chromosomes, with one chromosome from each pair inherited from each parent. When a genetic disorder occurs, there is an alteration in either the number or structure of these chromosomes. This alteration can affect either the autosomes or the sex chromosomes. However, it is worth noting that autosomal disorders often tend to be associated with more severe birth defects than abnormalities in the sex chromosomes. In the following discussion, we will explore several types of genetic number disorders.


Monosomy, which involves the presence of a single copy of a particular chromosome in a diploid organism, typically leads to severe developmental abnormalities and is often not compatible with life. This situation can indeed result in spontaneous abortion (miscarriage) in many cases because the embryo’s genetic imbalance and missing genetic material are not viable.


Trisomy, which involves the presence of an extra copy of a particular chromosome, is more commonly observed and can lead to genetic disorders. Some trisomies, such as Trisomy 21 (Down’s Syndrome), are survivable, although they can result in a range of developmental and health challenges. The impact of trisomy can vary depending on the specific chromosome involved and the extent of the genetic imbalance.


Two additional important terms related to chromosomal number disorders are polyploidy and triploidy.


Polyploidy refers to the presence of more than two complete sets of chromosomes in an organism’s cells. While most humans are diploid, meaning they have two sets of chromosomes (2n), polyploid organisms may have three (triploid, 3n), four (tetraploid, 4n), or more sets of chromosomes. Polyploidy is relatively less common in animals, including humans.


Triploidy is a specific type of polyploidy where an individual has three sets of chromosomes (3n). It often results from the fertilization of an egg by two sperm cells or, less commonly, from the fusion of a haploid sperm with a diploid egg. Triploidy is associated with significant developmental abnormalities and usually leads to miscarriage or stillbirth in humans. It’s considered a type of aneuploidy, where there is an abnormal number of chromosomes.


Down’s Syndrome can result in a variety of physical, intellectual, and developmental expressions. The specific features and their degree of severity may differ from one individual to another.


After implantation, the inner cell mass of the blastocyst that will become the embryo differentiates into two layers: the epiblast and the hypoblast. The epiblast then gastrulates into three germ layers: the ectoderm, mesoderm, and endoderm, and develops the embryo. At the same time, the hypoblast will form the extra-embryonic membranes: the yolk sac, amnion, and allantois.


Throughout fetal growth, many terms correlate to the cell division and the formation of the epiblast. Following the initial two weeks of development, the term “pre-embryo” is used to refer to the developing structure.  From three to eight weeks post-fertilization, the pre-embryonic cells become distinct and become the “embryo”.  Subsequently, from eight weeks post-fertilization until birth, the developing organism is referred to as the “fetus.”


During early development, cells in the embryo go through a process of differentiation, which involves becoming specialized to perform specific functions. The position of a given cell relative to others can play a crucial role in determining its fate or the specific genes it will express. This concept is known as spatial patterning, or positional information, and implies that the location of a cell within the developing embryo influences the genes it activates and the type of cell it will become.


In addition to the differentiation of various cell types, many essential structures and organs form to support the growing embryo and fetus, including the placenta, umbilical cord and amniotic fluid. As the embryo develops into a fetus, these supportive structures become increasingly important for the well-being of the growing fetus. They play critical roles in ensuring that the fetus receives the necessary nutrients, oxygen, and protection for healthy development. The placenta, umbilical cord, and amniotic fluid are intricately linked in their functions, forming a nurturing environment for the fetus throughout pregnancy.


Morphogenesis refers to the shaping and structuring of an organism’s form. It encompasses a series of intricate processes responsible for the emergence of the body’s diverse systems and organs. This developmental journey is a continuous maturation, with all systems and organs initiating their formation in the early stages of pregnancy, primarily within the first eight weeks of gestation, and their progression continues throughout the gestational period. This gradual maturation prepares the fetus for its eventual transition to life outside the womb. Three critical organs that undergo development and determine the potential for fetal survival and health are the heart, lungs, and nervous system. Their maturation and functions are discussed below.


are the heart, lungs, and nervous system. Their maturation and functions are discussed below.


The cardiovascular system, including the heart, is one of the earliest functional systems to develop, with the sound of the heartbeat becoming audible as early as five weeks through vaginal probe or by normal stethoscope at week twelve.


Lung maturity is a critical aspect of fetal development and occurs toward the end of pregnancy, with the proper production of surfactant, a substance produced by special cells in developing fetal lungs. Surfactant plays a crucial role in reducing surface tension in the alveoli (tiny air sacs in the lungs). The maturation of the lungs refers to the readiness of a fetus’s lungs to function effectively in supporting respiration once the infant is born.


The formation of the nervous system, including the central nervous system (CNS) and peripheral nervous system (PNS), begins very early in embryonic development. The neural tube, which eventually becomes the brain and spinal cord, forms as others during the first eight weeks after conception. Fat deposition and myelin formation occur later in fetal development, typically in the third trimester. Myelin is a fatty substance that surrounds nerve fibers and plays a crucial role in the rapid transmission of nerve impulses. This process continues throughout pregnancy and even after birth.


Infants who are born before they have reached full term are at higher risk for various complications because some of their organs and systems may not have fully matured.  For example, the risk of respiratory distress in premature infants is a significant concern because the lungs typically require the last few weeks of pregnancy to develop fully and become fully functional at birth.


Medical professionals closely monitor lung maturity, especially when managing pregnancies that might be at risk for preterm birth. When necessary, interventions may be taken to support lung development, including the administration of corticosteroids to stimulate surfactant production in the lungs and improve lung maturity.


Uncontrolled urination or defecation in a newborn, often referred to as “involuntary voiding” or “involuntary bowel movements,” is indeed a common occurrence. This is primarily due to the immaturity of the nervous system and the myelin sheath at birth.


As the nervous system and myelin sheath continue to mature after birth, infants gradually gain control over these functions. By the age of 2 or 3, most children have developed the ability to voluntarily control urination and bowel movements and have achieved toilet training milestones.


The reproductive system is one of the few systems that matures differently based on the sex of embryos. Sex determination is completed at fertilization. It is well known that females have two X chromosomes, while males have one X and one Y. Since all eggs carry X chromosomes, the determination of sex is reliant on the sperm’s contribution. If the sperm has the Y chromosome, the SRY gene is activated, which initiates the expression of the Testis-Determining Factor (TDF) and leads to the development of the testes. Nevertheless, it is important to note that it takes time for the gonads to differentiate into their final form.


At week five of development, a paired bulge is present near the midline at the back of the abdominal cavity. These are the genital ridges and are indifferent in males and females. Germ cells from the yolk sac will then migrate toward the genital ridges. Only a week later, indifferent accessory ducts are present. These are the paramesonephric and mesonephric ducts. It is important to note that external genitalia of the different genders also arise from the same structures: the genital tubercle, urogenital folds, and labioscrotal swellings.


At week seven, male structures begin to develop. Primordial germ cells that are XY develop the testis, which secrete testosterone. In males, the paramesonephric ducts degenerate, and the mesonephric ducts develop the accessory ducts and glands of the reproductive system. Until two months before birth, the testes are located in the pelvic cavity. Once stimulated by testosterone the testes then descend into the scrotum. The scrotum is an external structure developed from labioscrotal swelling due to testosterone influence. This hormone also causes the genital tubercle to enlarge, forming the penis and the urogenital fold to form the ventral aspect of the penis.


At week eight, female structures begin to develop. Primordial germ cells that are XX develop the ovaries that eventually descend into the pelvic cavity to be stopped by the broad ligament at the pelvic brim. Degeneration of the mesonephric ducts occurs, and the paramesonephric ducts develop into the oviduct and female genital tract. In the absence of testosterone, the genital tubercle develops into the clitoris, the urethral groove remains open to develop into the vestibule, the urogenital fold becomes the labia minora, and the labioscrotal swellings form into the labia majora.


The placenta gradually takes over the corpus luteum’s duties in the secretion of estrogen and progesterone. By the end of the first trimester, the placenta becomes the primary source of estrogen and progesterone and is responsible for the continuation of pregnancy, taking over the role of feeding the embryo.


The placenta usually connects to the conceptus via the umbilical cord, which contains the umbilical vessels. The spaces within the cord and around the blood vessels are filled with Wharton’s jelly, a mucous connective tissue. The umbilical cord and vessels aid in the transfer of oxygen, nutrients, and waste products without mixing maternal and fetal blood. Deoxygenated blood and waste leaves the fetus through two umbilical arteries, while nutrients and oxygen are carried from the mother to the fetus through a single umbilical vein. The umbilical cord is surrounded by the amnion. The placenta’s initial development as an organ is complete by weeks 14–16 after fertilization.


contains the umbilical vessels. T


he spaces within the cord and around the blood vessels are filled with Wharton’s jelly, a mucous connective tissue.


The umbilical cord and vessels aid in the transfer of oxygen, nutrients, and waste products without mixing maternal and fetal blood. Deoxygenated blood and waste leaves the fetus through two umbilical arteries, while nutrients and oxygen are carried from the mother to the fetus through a single umbilical vein. The umbilical cord is surrounded by the amnion. The p


lacenta’s initial development as an organ is complete by weeks 14–16 after fertilization.


The placenta grows like an expanding disk. By week 20, the placenta covers half of the uterine wall and weighs about 200g. At term, it is about 700g and 20cm in diameter. The placenta is highly vascular and if the baby dies or is delivered, the placenta can keep growing.


Because blood cells cannot move across the placenta, the maternal and fetal blood do not co-mingle. This separation prevents the mother’s cytotoxic T cells from reaching and subsequently destroying the fetus, which bears “non-self” antigens. Further, it ensures the fetal red blood cells do not enter the mother’s circulation and trigger antibody development (if they carry “non-self” antigens) until the final stages of pregnancy or birth. This separation is why, even in the absence of preventive treatment, an Rh− mother doesn’t develop antibodies that could cause hemolytic disease in her first Rh+ fetus.


Although blood cells are not exchanged, the placenta is permeable to lipid-soluble fetotoxic substances: alcohol, nicotine, barbiturates, antibiotics, certain pathogens, and many other substances that can be dangerous or fatal to the developing embryo or fetus. For these reasons, pregnant women should avoid fetotoxic substances.


The placenta is normally attached and situated in the upper one-third of the anterior or posterior uterine wall within the endometrium. This placement is conducive to the growth and development of the embryo.


Implantation of the placenta occurs in the lower part of the uterus. A place can result in the partial or complete coverage of the cervical os. As the highly vascularized nature of the placenta, bleeding may occur with the growing uterus, and early or partial separation of the placenta may happen, and continuation of pregnancy will be jeopardy.


bleeding may occur with the growing uterus, and early or partial separation of the placenta may happen, and continuation of pregnancy will be jeopardy.


bleeding may occur with the growing uterus, and early or partial separation of the placenta may happen, and continuation of


A condition characterized by placenta attachment directly into the myometrium, placenta accreta is often caused by defective decidual endometrial layers, uterine inflammation, or old scar tissue from previous cesarean or uterine surgery. Tied placental implantation in the myometrium will impair placental separation after birth, resulting in massive bleeding and hemorrhage that may even lead to the death of the mother.


characterized by placenta attachment directly into the myometrium, placenta accreta is often caused by defective decidual endometrial layers, uterine inflammation, or old scar tissue from previous cesarean or uterine surgery. Tied placental implantation in the myometrium will impair placental


As the zona pellucida begins to fragment, the blastocyst is able to attach to the uterine endometrium. By this time, progesterone and estrogen produced by the corpus luteum lead to the proper proliferation and differentiation of the endometrium. As the endometrium continues its maturation, a decidua layer is formed. The maturation of the endometrium and formation of a secretory endometrium is called decidualization.  Around the end of the first week, the blastocyst comes into contact with the secretory uterine wall and adheres to it, embedding itself in the uterine lining via the trophoblast cells. Thus begins the process of implantation.


The inner cell layer of the trophoblast of the blastocyst, called the cytotrophoblast, forms the fetal surface of the placenta. The outer layer of the trophoblast, known as the syncytiotrophoblast, contributes to the maternal surface of placenta that fuses with endometrial cells. The syncytiotrophoblast cells lose their cell walls and become the working interface of the placenta. The cytoplasm of the cells fuse and form a multinucleated cytoplasm. Then, the syncytiotrophoblast layer invaginates into the decidua and is surrounded by lakes of maternal blood, allowing the efficient transfer of oxygen, nutrients, and waste products bidirectionally without the direct mixing of maternal and fetal blood.


The syncytiotrophoblast cells produce human chorionic gonadotropin (hCG), a hormone that directs the corpus luteum to survive, enlarge, and continue producing progesterone and estrogen to suppress menses. These functions of hCG are necessary for creating an environment suitable for the developing embryo. As a result of this increased production, hCG accumulates in the maternal bloodstream and is excreted in the urine. Implantation is complete by the middle of the second week. Just a few days after implantation, the trophoblast has secreted enough hCG for an at-home urine pregnancy test to give a positive result. hCG is the marker used for mass pregnancy tests.


Implantation can be accompanied by minor bleeding. The blastocyst typically implants in the fundus of the uterus or on the posterior wall. However, if the endometrium is not fully developed and is not ready to receive the blastocyst, the blastocyst will detach and find a better spot. A significant percentage (50–75 percent) of blastocysts fail to implant; when this occurs, the blastocyst is shed with the endometrium during menses. The high rate of implantation failure is one reason why pregnancy typically requires several ovulation cycles to achieve.


The time from ovulation to implantation takes approximately 10–12 days. Proper timing for the arrival of the conceptus into the uterine cavity is essential for implantation. During IVF techniques, the maturation of the endometrium must be coordinated precisely with the developmental stage of the conceptus transferred into the uterus for optimal pregnancy rates. Attempts at tubal re-anastomosis may be followed by too short of the oviduct (<4cm). Short tubes might accelerate the transport of the conceptus through the tubes and diminish pregnancy rates.


Proper timing for the arrival of the conceptus into the uterine cavity is essential for implantation. During IVF techniques, the maturation of the endometrium must be coordinated precisely with the developmental stage of the conceptus transferred into the uterus for optimal pregnancy rates.


Attempts at tubal re-anastomosis may be followed by too short of the oviduct (<4cm). Short tubes might accelerate the transport of the conceptus through the tubes and diminish pregnancy rates.


Following fertilization, the zygote and its associated membranes, together referred to as the conceptus, continue to be projected toward the uterus by peristalsis and beating cilia. During its journey to the uterus, the zygote undergoes five or six rapid mitotic cell divisions. The rapid, multiple rounds of cell division are termed cleavage. Although each cleavage results in more cells, it does not increase the total volume of the conceptus. Each daughter cell produced by cleavage is called a blastomere.


Approximately 72 hours after fertilization, a 16-cell conceptus reaches the uterus. The cells that had been loosely grouped are now compacted and look more like a solid mass. The name given to this structure is the morula.


Once inside the uterus, the conceptus floats freely for several more days. It continues to divide, creating a ball of approximately 100 cells and consuming nutritive endometrial secretions called uterine milk while the uterine lining thickens. The ball of the tightly bound cells starts to secrete fluid and form a central fluid-filled cavity. At this developmental stage, approximately 5 days after ovulation, the conceptus is referred to as a blastocyst.


Within the blastocyst, the cells arrange themselves into two layers. A group of cells forms into an inner cell mass which is fated to become the embryo. The cells that form the outer shell, called trophoblasts, will develop into the placenta (the organ of nutrient, waste, and gas exchange between mother and the developing embryo).


As the blastocyst forms, the trophoblast excretes enzymes that begin to degrade the zona pellucida. In a process called “hatching,” the conceptus breaks free of the zona pellucida in preparation for implantation.


Up to the 8-cell stage of cleavage, the cells of the conceptus are pluripotent cells, where each cell has the potential to differentiate into any cell type in the human body, and each can be independently developed into an identical conceptus. These cells are called embryonic stem cells (ESC) and are widely used in scientific research to better understand early human development, study diseases, and develop potential treatments. ESCs provide a valuable model for studying cell differentiation and developmental processes; however, research involving ESCs has been a topic of ethical debate because their extraction usually involves the destruction of human embryos.


Identical twins are the result of a single fertilized egg (oocyte) splitting into two embryos. This splitting typically occurs shortly after fertilization, but it can happen at various stages of development, including before the 16-cell stage.


When the single fertilized egg splits into two embryos, these twins share the same genetic material, making them genetically identical. Because they come from the same fertilized egg, they are of the same sex and usually share a strong resemblance in terms of physical appearance. Identical twins are sometimes called “monozygotic twins” to highlight their single-egg origin.


The journey through the female reproductive system to reach the oocyte is thought to be facilitated by uterine contractions which usually take around 30 minutes to 2 hours. A healthy sperm could reach the ampulla within 30 minutes. If the sperm do not encounter an oocyte immediately, they can survive in the uterine tubes for another 48–72 hours. Thus, fertilization can still occur if intercourse takes place a few days before ovulation. In comparison, an oocyte can survive independently for only approximately 24 hours following ovulation. Therefore, intercourse more than a day after ovulation will usually not result in fertilization.


During the journey, fluids in the female reproductive tract prepare the sperm for fertilization through a process called capacitation, or priming. The fluids improve the motility of the spermatozoa. They also deplete cholesterol molecules embedded in the membrane of the head of the sperm, thinning the membrane in such a way that will help facilitate the release of the lysosomal (digestive) enzymes needed for the sperm to penetrate the oocyte’s exterior once contact is made. Sperm must undergo the process of capacitation to have the “capacity” to fertilize an oocyte. If they reach the oocyte before capacitation is complete, they will be unable to penetrate the oocyte’s thick outer layer of cells.


Upon ovulation, the oocyte released by the ovary is swept into—and along—the uterine tube. Fertilization must occur in the distal uterine tube because an unfertilized oocyte cannot survive the 72-hour journey to the uterus. The released oocyte is a secondary oocyte surrounded by two protective layers. The corona radiata is an outer layer of follicular (granulosa) cells that form around a developing oocyte in the ovary and remain with it upon ovulation. The underlying zona pellucida (pellucid = “transparent”) is a transparent, but thick, glycoprotein membrane that surrounds the cell’s plasma membrane.


As the oocyte is swept along the distal uterine tube, the oocyte encounters the surviving capacitated sperm, which stream toward it in response to chemical attractants released by the cells of the corona radiata. To reach the oocyte itself, the sperm must penetrate the two protective layers. The sperm first burrow through the cells of the corona radiata. Then, upon contact with the zona pellucida, the sperm bind to receptors in the zona pellucida. This initiates a process called the acrosomal reaction, in which the enzyme-filled “cap” of the sperm, called the acrosome, releases its stored digestive enzymes. These enzymes clear a path through the zona pellucida, allowing sperm to reach the oocyte. Finally, a single sperm makes contact with sperm-binding receptors on the oocyte’s plasma membrane. The plasma membrane of the sperm then fuses with the oocyte’s plasma membrane, and the head and mid-piece of the “winning” sperm enter the oocyte interior.


How do sperm penetrate the corona radiata? Some sperm undergo a spontaneous acrosomal reaction, an acrosomal reaction that is not triggered by contact with the zona pellucida. The digestive enzymes released by this reaction digest the extracellular matrix of the corona radiata. As you can see, the first sperm to reach the oocyte is never the one to fertilize it. Rather, hundreds of sperm cells must undergo the acrosomal reaction, each helping to degrade the corona radiata and zona pellucida until a path is created to allow one sperm to contact and fuse with the oocyte’s plasma membrane.


When the first sperm fuses with the oocyte, the oocyte deploys two mechanisms to prevent polyspermy, or penetration by more than one sperm. Preventing polyspermy is critical because if more than one sperm were to fertilize the oocyte, the resulting zygote would be a triploid organism with three sets of chromosomes, and incompatible with life.


When the first sperm fuses with the oocyte, the oocyte deploys two mechanisms to prevent


, or penetration by more than one sperm. Preventing polyspermy is critical because if more than one sperm were to fertilize the oocyte, the resulting zygote would be a triploid organism with three sets of chromosomes, and incompatible with life.


The first mechanism is the fast block, which involves a near-instantaneous change in sodium ion permeability upon the binding of the first sperm, depolarizing the oocyte plasma membrane and preventing the fusion of additional sperm cells. The fast block sets in almost immediately and lasts for about a minute.


At the same time, an influx of calcium ions following sperm penetration triggers the second mechanism, the slow block. In this process, referred to as the cortical reaction, cortical granules sitting immediately below the oocyte plasma membrane fuse with the membrane and release zonal inhibiting proteins and mucopolysaccharides into the space between the plasma membrane and the zona pellucida. Zonal inhibiting proteins cause the release of any other attached sperm and destroy the oocyte’s sperm receptors, thus preventing any more sperm from binding. The mucopolysaccharides then coat the nascent zygote in an impenetrable barrier that, together with the hardened zona pellucida, is called a fertilization membrane, or eggshell.


Recall that at the point of fertilization, the oocyte has not yet completed meiosis; all secondary oocytes remain arrested in metaphase of meiosis II until fertilization. Only upon fertilization does the oocyte complete meiosis. The unneeded complement of genetic material that results is stored in a second polar body that is eventually ejected. At this moment, the oocyte has become an ovum, the female haploid gamete. The two haploid nuclei derived from the sperm and oocyte and contained within the egg are referred to as pronuclei. They decompress, expand, and replicate their DNA in preparation for mitosis. The pronuclei then migrate toward each other, their nuclear envelopes disintegrate, and the male- and female-derived genetic material intermingles. This step completes the process of fertilization and results in a single-celled diploid zygote with all the genetic instructions it needs to develop into a human. Sex, hair and eye color determination happen at this point.


Fraternal twins, also known as dizygotic twins, are a type of twins that result from the simultaneous release and fertilization of two different eggs (oocytes) by two different sperm cells. Fraternal twins are essentially like any other siblings, with the key difference being that they share the same womb during pregnancy.


Because they develop from separate fertilized eggs, they have their own unique genetic makeup and can be of the same gender (two brothers or two sisters) or of different genders (a brother and a sister). They share approximately 50% of their genes, like any other siblings born at different times.


Early pregnancy factor (EPF) is a protein that has been used to describe a substance in the mother’s blood that seems to be present within hours after conception (fertilization), before the embryo even reached the uterus. This factor might be involved in preventing the mother’s immune system from rejecting the developing embryo. Ongoing research is attempting to identify and characterize the specific molecules or factors involved in early pregnancy, although a universally accepted explanation has yet to be established.


In contrast, meiosis is a crucial mechanism for generating new cells through sexual reproduction. Meiosis involves two distinct stages, meiosis I and meiosis II, which are essential during gametogenesis to produce four unique haploid daughter cells.


In both cycles, DNA replication occurs first, where the nuclear membrane breaks down and the organism’s DNA condenses to form chromosomes. A key difference between mitosis and meiosis is that during meiosis, when the chromosomes come together, they “cross over,” which allows for the exchange and “mixing” of the DNA coding. After that, the chromosomes separate and migrate to the opposite ends of the cell. Upon the completion of meiosis I and II, the cell divides into 4 distinct, haploid daughter cells, each with its own characteristics.


key difference between mitosis and meiosis is that during meiosis, when the chromosomes come together, they “cross over,” which allows for the exchange and “mixing” of the DNA coding. After that, the chromosomes separate and migrate to the opposite ends of the cell. Upon the completion of meiosis I and II, the cell divides into 4