Fetal cardiac development begins early in gestation and follows a tightly regulated sequence of events that culminates in detectable cardiac activity. Cardiac tube formation, heartbeat initiation, ultrasound visualization, and valvular development are essential benchmarks. The fetal heart begins rhythmic contraction by day 22–23 post-conception, equivalent to week 5 gestation, and is typically detectable by transvaginal ultrasound by week 6 gestation. Heart rate ranges from 90–110 bpm at week 6, rising to 140–170 bpm by week 9. Visualization depends on equipment quality and maternal habitus, but week 6 remains the accepted norm in clinical guidelines.

Rationale for correct answers

B. Week 6 marks the earliest point at which transvaginal ultrasound can reliably detect fetal cardiac activity. The heart begins beating at 22–23 days post-fertilization, and by week 6 gestation, this activity is visible with sensitive ultrasound probes. The presence of cardiac motion at this stage confirms a viable intrauterine pregnancy.

Rationale for incorrect answers

A. At week 4, the fetal heart is still forming as a simple cardiac tube and has not yet initiated contractions. Although organogenesis has begun, cardiac activity cannot yet be visualized by ultrasound at this stage.

C. While fetal heart activity is clearly detectable by week 8, this is later than the earliest detectable point. Waiting until week 8 delays diagnosis of viability, particularly in early pregnancy assessments or evaluations for ectopic pregnancy.

D. By week 10, the fetal heart is well developed and easily visualized, but this is significantly later than necessary for initial viability assessments. Ultrasound at this point may assess more than viability, such as rhythm or structural anomalies.

Take home points

• Fetal cardiac activity begins at 22–23 days post-conception and is visible on ultrasound by week 6.

• Week 6 is the standard gestational age for confirming cardiac motion via transvaginal ultrasound.

• By week 8–10, fetal heart structures are more developed, but detection occurs earlier.

• Absence of cardiac activity at or after week 6 may suggest pregnancy failure if gestational dating is accurate.

Organogenesis is the phase in embryonic development during which organ systems form, making the embryo highly vulnerable to teratogens. The nervous system is the first major structure to develop, beginning in week 3, and continues through week 8 and beyond. Neural tube formation begins at day 18–21 and closes by day 28. Exposure to teratogens during this critical period can cause irreversible damage such as anencephaly or spina bifida. Folic acid deficiency is a leading cause of neural tube defects. The neural tissue remains susceptible longer than most other systems due to its prolonged development.

Rationale for correct answers

C. The nervous system is the most vulnerable to teratogens at 8 weeks gestation because this is the peak of its morphogenesis. By 8 weeks, the neural tube has closed, and rapid differentiation of the brain and spinal cord occurs. Disruption at this stage results in structural anomalies like hydrocephalus, anencephaly, or microcephaly.

Rationale for incorrect answers

A. The respiratory system begins development around week 4, but its critical period of vulnerability to teratogens occurs much later, primarily in the pseudoglandular and canalicular phases, from weeks 5 to 17 and 16 to 25 respectively. However, full maturation extends into the third trimester, making week 8 less critical for major structural anomalies.

B. The cardiovascular system begins forming at week 3 and is largely complete by week 8. Most congenital heart defects result from teratogenic exposure earlier in the first trimester. By week 8, major septation and outflow tract formation are usually complete, so this period is less vulnerable.

D. The musculoskeletal system starts developing in week 4 and continues throughout gestation. Although it is still differentiating at week 8, the most teratogen-sensitive window is earlier when somites are forming and limb buds are initiating (weeks 4 to 7). By week 8, musculoskeletal anomalies are less likely from new teratogenic insults.

Take home points

• The nervous system has the longest teratogen-sensitive period due to its early start and prolonged development.

• Week 8 is critical for brain and spinal cord differentiation, making neural tissue highly vulnerable.

• Cardiovascular defects originate earlier, typically between weeks 3 and 6.

• Teratogenic effects depend on timing, with different systems having unique windows of susceptibility.

Folic acid metabolism plays a critical role in early embryogenesis, particularly during neural tube closure. This process begins at day 18 post-conception and completes by day 28. Folic acid is required for DNA synthesis, cell division, and methylation reactions, which are essential during rapid cellular proliferation in early fetal development. The recommended daily intake is 400–800 mcg prior to conception and during the first trimester. Deficiency significantly increases the risk of neural tube defects such as spina bifida and anencephaly.

Rationale for correct answers

B. Folic acid prevents neural tube defects by supporting DNA synthesis and rapid cell division required for proper neural tube closure between days 18 and 28 post-conception. Supplementation before and during early pregnancy reduces neural tube defects by up to 70%.

Rationale for incorrect answers

A. Folic acid does not directly enhance fetal weight gain. Fetal growth is influenced by factors such as placental function, maternal nutrition overall, and gestational age, not folic acid alone.

C. While folic acid indirectly supports red blood cell production, its primary function in pregnancy is to prevent neural tube defects. Iron and vitamin B12 are more directly involved in hemoglobin synthesis.

D. Folic acid does not reduce the risk of gestational diabetes. Risk factors for gestational diabetes include obesity, family history, and insulin resistance. There is no strong evidence that folic acid modifies glucose metabolism.

Take home points

• Folic acid is essential for neural tube closure between days 18 and 28 post-conception.

• Supplementation reduces the risk of neural tube defects such as anencephaly and spina bifida.

• Recommended intake is 400–800 mcg daily before conception through the first trimester.

• Folic acid does not directly affect fetal weight gain or maternal glucose regulation.

Embryo-to-fetus transition is marked by the completion of organogenesis and the beginning of growth and maturation phases. The embryonic period spans from implantation until the end of week 8, during which all major organ systems form. By the start of week 9, the organism is termed a fetus, reflecting the shift toward structural refinement and functional development. Critical processes such as neurulation, cardiac looping, and limb bud formation occur during this phase. The crown-rump length at this stage is approximately 30 mm, and fetal heart rate ranges between 140–170 bpm.

Rationale for correct answers

C. Week 8 marks the final week of the embryonic period, after which the developing organism is termed a fetus. This transition occurs at the beginning of week 9, following the completion of major organ system formation during the embryonic stage.

Rationale for incorrect answers

A. Week 4 is early in the embryonic period, when organogenesis has just begun. At this stage, processes such as gastrulation and early neural development are occurring, and the term "fetus" is not yet applicable.

B. Week 6 is mid-embryonic development. Organ systems, including the heart and neural tube, are actively forming, and the embryo is undergoing rapid morphogenesis. It is still scientifically referred to as an embryo.

D. Week 12 is well into the fetal period. By this time, organ systems are formed and are undergoing functional maturation. However, the transition from embryo to fetus has already occurred by the start of week 9.

Take home points

• The embryonic period ends at the close of week 8 gestation.

• The fetus begins at week 9, focusing on growth and functional maturation.

• Organogenesis occurs during weeks 3–8, making this a teratogen-sensitive phase.

• Terminology shift reflects developmental milestones, not fetal viability.

Fertilization involves a series of tightly regulated cellular events that allow a single sperm to penetrate the oocyte and initiate embryogenesis. These include capacitation, acrosomal reaction, cortical reaction, and syngamy. Capacitation occurs in the female reproductive tract and enhances sperm motility and membrane fluidity. The acrosomal reaction enables enzymatic digestion of the zona pellucida, while the cortical reaction blocks polyspermy through release of cortical granules. Normal fertilization occurs in the ampulla of the fallopian tube. Diploid zygote formation with 46 chromosomes follows nuclear fusion.

Rationale for correct answers

A. Capacitation is a prerequisite for successful fertilization. It occurs in the female reproductive tract and involves cholesterol efflux and membrane destabilization, which prepare the sperm for the acrosomal reaction.

B. The cortical reaction occurs immediately after the sperm penetrates the oocyte membrane. It involves exocytosis of cortical granules that modify the zona pellucida to prevent polyspermy, ensuring monospermic fertilization.

E. The acrosomal reaction allows the sperm to penetrate the zona pellucida by releasing hydrolytic enzymes like hyaluronidase and acrosin. This reaction is essential for sperm entry into the oocyte.

Rationale for incorrect answers

C. Implantation occurs several days after fertilization, typically between days 6–10 post-fertilization. It is not part of the fertilization process but rather a post-fertilization embryonic event involving trophoblast invasion of the endometrium.

D. Gastrulation occurs in the third week of development. It marks the formation of the three germ layers (ectoderm, mesoderm, endoderm) and is a post-implantation embryonic process, not part of fertilization.

Take home points

• Capacitation prepares sperm for fertilization by enhancing motility and membrane changes.

• Acrosomal reaction is essential for sperm penetration through the zona pellucida.

• Cortical reaction prevents polyspermy and ensures successful monospermic fertilization.

• Implantation and gastrulation are post-fertilization events and occur days later.

Fetal skin development progresses in defined stages, influenced by keratinization, hair follicle formation, and sebaceous gland activity. By the early second trimester (weeks 13–16), the fetus begins producing lanugo—fine, unpigmented hair—and vernix caseosa, a lipid-rich, white protective substance. Lanugo helps anchor vernix to the skin, while vernix caseosa provides barrier protection, prevents fluid loss, and has antimicrobial properties. Subcutaneous fat, by contrast, begins to accumulate significantly in the third trimester, particularly after week 28.

Rationale for correct answers

D. Both lanugo and vernix caseosa begin to form in the early second trimester. Lanugo appears first and facilitates the adherence of vernix caseosa, which is secreted by fetal sebaceous glands. Their formation marks key protective adaptations of fetal skin.

Rationale for incorrect answers

A. Subcutaneous fat does not begin to accumulate until the third trimester. Fat deposition accelerates after week 28 and continues until term, helping with thermoregulation and energy storage postpartum.

B. Lanugo begins to form around weeks 13–16 and is a normal early second-trimester feature. However, it is not the only structure that forms at this time, making this answer incomplete.

C. Vernix caseosa begins to develop alongside lanugo in the early second trimester. It alone does not represent the full scope of what occurs during this period, making this option incomplete.

Take home points

• Lanugo and vernix caseosa both begin forming in the early second trimester.

• Subcutaneous fat accumulates later, primarily in the third trimester.

• Vernix caseosa has antimicrobial and barrier functions in fetal skin protection.

• Lanugo helps retain vernix on the fetal skin surface.

Quickening refers to the first maternal perception of fetal movement, typically occurring between 18 and 20 weeks gestation in nulliparous women and as early as 16 weeks in multiparous women. It results from increased neuromuscular coordination, fetal strength, and uterine wall sensitivity. Quickening is influenced by placental location, with posterior placentas allowing earlier detection than anterior ones. These movements are critical indicators of neurologic integrity and fetal viability and become more regular as gestation advances.

Rationale for correct answers

A. Quickening is defined as the first sensation of fetal movement perceived by the pregnant person. It generally occurs around 18–20 weeks in first pregnancies due to lower uterine sensitivity and around 16 weeks in subsequent pregnancies due to increased awareness. The movement represents advancing fetal neuromuscular development.

Rationale for incorrect answers

B. The rapid growth spurt occurs during the second trimester but is not related to maternal perception of fetal movement. Fetal length increases from approximately 9 cm at week 12 to 25 cm by week 20, but this process is silent to maternal sensation.

C. Braxton Hicks contractions are irregular, painless uterine contractions that begin in the second trimester but typically intensify in the third. They are not perceived as fetal movement and are unrelated to the neurologic activity of the fetus.

D. Engagement of the fetal head, also called lightening, occurs near term when the presenting part descends into the pelvic inlet. This mechanical process is different from fetal movement and occurs later, usually after 36 weeks in primigravida.

Take home points

• Quickening is the first perceived fetal movement, typically at 18–20 weeks gestation.

• It is earlier in multiparous women and later in primigravida.

• It reflects fetal neuromuscular maturation and uterine wall sensitivity.

• It must be differentiated from Braxton Hicks contractions and lightening.

Fetal movement perception is a physiologic milestone influenced by gestational age, parity, uterine sensitivity, and placental location. In primigravida mothers, the first perception of fetal movement—quickening—typically occurs between weeks 18 and 20, though it may be reported as early as week 16. Multiparous women may notice movement earlier due to heightened neuromuscular awareness and abdominal wall laxity. Fetal movement frequency increases after week 20 and becomes more organized as the central nervous system matures. Movements are associated with intact neurologic and musculoskeletal systems and are a marker of fetal well-being.

Rationale for correct answers

B. Weeks 16–20 are when fetal movements become perceptible to most primigravida mothers. The first movements are usually felt at 18–20 weeks due to the lower sensitivity of the uterine wall and unfamiliarity with fetal activity in first-time pregnancies. This timeframe reflects neurologic maturation and increasing fetal strength.

Rationale for incorrect answers

A. Fetal movement at weeks 12–14 is minimal and not strong enough to be perceived by the mother. Although spontaneous movements occur by week 7–8 on ultrasound, they are too subtle for maternal detection this early.

C. While fetal movements are definitely present by weeks 21–24, this is later than the expected window for initial perception in primigravida mothers. Most first-time mothers have already reported quickening by this stage.

D. Weeks 25–28 are well beyond the expected time of initial fetal movement perception. Movements during this stage are more forceful and regular but should not be the first perceived movements in a normal pregnancy.

Take home points

• Primigravida mothers typically perceive fetal movement at 18–20 weeks gestation.

• Movements may be felt as early as week 16 but rarely before.

• Earlier perception is more common in multiparous women.

• Delayed perception beyond 20 weeks may require clinical evaluation.

Second-trimester fetal assessment focuses on evaluating structural development, growth parameters, and anomalies. The most commonly used diagnostic tool is ultrasound, particularly the anatomy scan or level II ultrasound, typically done between 18 and 22 weeks. It assesses fetal biometry, organ structure, amniotic fluid volume, placental location, and fetal sex. Normal biparietal diameter (BPD) at 20 weeks is approximately 45–52 mm, femur length (FL) is 30–32 mm, and amniotic fluid index (AFI) ranges from 8 to 18 cm. Ultrasound is non-invasive, safe, and widely accessible.

Rationale for correct answers

C. Ultrasound is the most commonly used diagnostic test in the second trimester for evaluating fetal development. The detailed anatomy scan performed at 18–22 weeks assesses organ formation, fetal measurements, and detects structural abnormalities such as neural tube or cardiac defects. It is non-invasive and provides real-time imaging.

Rationale for incorrect answers

A. Non-stress test (NST) is used in the third trimester, typically after 28 weeks, to assess fetal heart rate patterns in response to movement. It evaluates fetal well-being in high-risk pregnancies but does not assess fetal anatomy or development in the second trimester.

B. Amniocentesis can be performed in the second trimester (usually after 15 weeks), but it is not a routine assessment of fetal development. It is an invasive diagnostic test used for genetic testing, lung maturity, or infection evaluation when indicated.

D. Biophysical profile is done later in pregnancy, typically after 28 weeks, to assess fetal well-being using ultrasound and NST. It evaluates fetal breathing, tone, movement, and amniotic fluid but is not used for developmental assessment during the second trimester.

Take home points

• Ultrasound is the standard second-trimester test to assess fetal anatomy and growth.

• Detailed anatomy scans are done between 18 and 22 weeks.

• NST and biophysical profiles are third-trimester assessments of fetal well-being.

• Amniocentesis is used selectively for genetic diagnosis, not routine development screening.

Second trimester development (weeks 14–27) is characterized by fetal growth, organ maturation, and increasing structural refinement rather than initial organogenesis, which concludes by week 8. During this period, vernix caseosa begins forming around week 20, external genitalia become clearly distinguishable on ultrasound by weeks 16–18, and lanugo emerges but does not disappear until the third trimester. Subcutaneous fat starts accumulating in the third trimester, particularly after week 28, and is critical for postnatal thermoregulation and energy metabolism.

Rationale for correct answers

C. Vernix caseosa begins to cover the fetal skin in the second trimester, typically starting around week 20. It is secreted by sebaceous glands and composed of water, lipids, and desquamated epithelial cells, providing barrier and antimicrobial protection.

D. External genitalia are usually well-differentiated and visible on ultrasound by weeks 16–18, allowing accurate determination of fetal sex. Genital differentiation is hormonally regulated and is typically complete by the mid-second trimester.

Rationale for incorrect answers

A. Significant subcutaneous fat accumulation occurs in the third trimester, primarily after week 28. Before this, the fetus appears thin and translucent due to minimal fat stores. Fat deposition is essential for thermal insulation and energy storage after birth.

B. Lanugo begins to form during the early second trimester (around weeks 13–16) and does not disappear by the end of the trimester. It typically persists into the third trimester, disappearing closer to term, around weeks 36–38.

E. Organogenesis is the hallmark of the first trimester, concluding by week 8. The second trimester focuses on organ growth, functional maturation, and morphologic development, not initial formation.

Take home points

• Vernix caseosa begins forming by week 20 for skin protection and moisture retention.

• External genitalia are usually visible on ultrasound by weeks 16–18.

• Subcutaneous fat develops later, mainly in the third trimester.

• Organogenesis ends in the first trimester; the second focuses on maturation.

Fetal growth in the second trimester follows a predictable pattern influenced by genetic, placental, and maternal factors. By week 26, the fetus typically weighs between 600 and 800 grams, with an average crown-to-heel length of 35–36 cm. The fetal weight increases rapidly from approximately 350 grams at week 22 to over 1,000 grams by week 28. Fetal lung development, muscle mass gain, and fat deposition also begin accelerating near the end of this period. Normal fetal growth parameters are assessed using biometric measurements such as femur length, abdominal circumference, and biparietal diameter.

Rationale for correct answers

B. At 26 weeks, the average fetal weight is approximately 760 grams, well within the range of 600–800 grams. This corresponds with fetal length of about 35 cm and increasing viability due to progressive lung and CNS maturation.

Rationale for incorrect answers

A. By week 26, the fetus exceeds 400 grams. A weight of 300–400 grams corresponds more closely to fetal parameters seen around week 20–22, not week 26.

C. A weight of 1–1.2 kg is typical around week 28–30, during early third trimester. At week 26, the fetus has not yet accumulated enough fat and muscle to reach this mass.

D. Weights of 1.5–2 kg occur in the late third trimester, generally around weeks 32–34. This is beyond the expected weight for a fetus at 26 weeks.

Take home points

• The average fetal weight at week 26 is approximately 760 grams.

• Fetal growth accelerates significantly after week 24 due to fat and muscle accumulation.

• Biometric measurements assess intrauterine growth and detect fetal growth restriction.

• Fetal viability improves significantly after week 24 due to organ maturation.

Fetal lung maturation is critical for extrauterine survival, particularly before 34 weeks gestation, when surfactant production is often insufficient. Betamethasone, a glucocorticoid, is administered intramuscularly to the pregnant person to stimulate type II alveolar cells to produce surfactant, primarily dipalmitoylphosphatidylcholine (DPPC). It crosses the placenta and promotes structural and biochemical maturation of the fetal lungs. The standard regimen is 12 mg intramuscularly every 24 hours for 2 doses. Benefits are greatest when birth occurs 24–48 hours after the first dose and include reduced risks of neonatal respiratory distress syndrome, intraventricular hemorrhage, and necrotizing enterocolitis.

Rationale for correct answers

B. Betamethasone is the drug of choice to enhance fetal lung maturity in preterm labor. It accelerates surfactant synthesis and lung development when administered between 24 and 34 weeks gestation, reducing neonatal respiratory morbidity.

Rationale for incorrect answers

A. Magnesium sulfate is used for neuroprotection in preterm infants <32 weeks and for seizure prophylaxis in preeclampsia, not lung maturation. It does not stimulate surfactant production.

C. Oxytocin is a uterotonic agent used to induce or augment labor, not to promote fetal lung maturity. Its administration would worsen preterm labor outcomes by promoting contractions.

D. Nifedipine is a calcium channel blocker used as a tocolytic to delay preterm labor. While it can prolong pregnancy, it does not directly influence surfactant production or lung development.

Take home points

• Betamethasone promotes fetal lung maturity by enhancing surfactant synthesis.

• It is administered between 24–34 weeks gestation in cases of preterm labor risk.

• Optimal benefit occurs within 24–48 hours of administration.

• Magnesium sulfate is for neuroprotection, not lung development.

Group B Streptococcus (GBS) screening is a universal prenatal test conducted to identify maternal colonization with Streptococcus agalactiae, which can cause early-onset neonatal sepsis, pneumonia, and meningitis. The screening is typically performed between 36 and 37 weeks gestation using a vaginal-rectal swab to best predict colonization status at delivery. Colonization can be transient, intermittent, or persistent, so testing too early may not reflect status at birth. If positive, intrapartum antibiotic prophylaxis (usually penicillin G) is recommended to reduce neonatal infection risk. GBS colonization does not typically cause maternal illness.

Rationale for correct answers

D. Screening is recommended between 36–37 weeks gestation because this timing best correlates with colonization status at delivery. Positive results prompt intrapartum antibiotic administration to prevent neonatal transmission during vaginal delivery.

Rationale for incorrect answers

A. Testing at 24–26 weeks is too early to accurately predict colonization status at term, since GBS colonization can change. Early testing may miss new colonization or clear existing transient colonization.

B. At 28–30 weeks, GBS screening is still premature. Colonization detected at this point does not reliably indicate presence at delivery, potentially leading to unnecessary or missed prophylaxis.

C. While 32–34 weeks is closer to delivery, it is still earlier than recommended. Testing at this stage may not reflect GBS status at term, reducing accuracy and predictive value.

Take home points

• GBS screening is optimally done at 36–37 weeks gestation.

• The test involves a vaginal-rectal swab to detect maternal colonization.

• Positive results require intrapartum penicillin to prevent neonatal GBS disease.

• Early testing is unreliable due to transient colonization.

Passive immunity in the fetus during the third trimester is primarily conferred by the transplacental transfer of maternal immunoglobulin G (IgG) antibodies. This process is facilitated by the neonatal Fc receptor (FcRn) in the placenta, which actively transports IgG from the maternal circulation to the fetal bloodstream. The transfer increases significantly after week 28, peaking near term, and provides temporary protection against pathogens such as measles, rubella, and tetanus. Other immunoglobulin classes, like IgM and IgA, do not cross the placenta. This maternal-fetal IgG transfer helps protect the neonate during the early postnatal period when the infant's immune system is still immature.

Rationale for correct answers

B. Maternal antibodies, specifically IgG, cross the placenta starting around 20 weeks but most significantly after 28 weeks. This provides the fetus with passive immunity to pathogens the mother has previously encountered or been vaccinated against, protecting the neonate until their own immune system matures.

Rationale for incorrect answers

A. The fetal liver produces immunoglobulins like IgM but cannot produce IgG in significant quantities. IgM is the first antibody synthesized by the fetus but does not confer maternal-derived passive immunity.

C. Amniotic fluid contains nutrients, hormones, and fetal waste products but does not deliver immunoglobulins systemically. While some immune cells may be present, it does not function in providing passive immunity.

D. Placental hormones (e.g., hCG, progesterone, estrogens) support pregnancy maintenance and fetal development but do not play a role in immune protection. They do not transfer antibodies or confer immune function.

Take home points

• IgG is the only antibody class that crosses the placenta to provide fetal immunity.

• Passive immunity transfer increases sharply after 28 weeks gestation.

• IgM and IgA do not cross the placenta and are synthesized by the fetus.

• Placental Fc receptors facilitate selective IgG transfer to the fetus.

Surfactant physiology is vital for fetal pulmonary development and neonatal respiratory function. Surfactant is a lipoprotein complex primarily composed of dipalmitoylphosphatidylcholine (DPPC), produced by type II alveolar cells beginning around week 20, with significant increases after week 32. Its main function is to reduce surface tension within the alveoli, preventing collapse during exhalation and enabling efficient lung expansion at birth. Surfactant also contributes to alveolar stability, compliance, and gas exchange. The lecithin-to-sphingomyelin (L/S) ratio, with a normal maturity value of ≥2:1, is a key indicator of fetal lung maturity.

Rationale for correct answers

B. Surfactant reduces surface tension at the air-liquid interface within alveoli, allowing them to remain open during respiration. This prevents atelectasis after the first breath, enabling effective lung inflation and gas exchange in the neonate.

Rationale for incorrect answers

A. Oxygen transport to the fetus occurs via placental gas exchange, not surfactant. Oxygenated maternal blood diffuses through the placenta to the fetal circulation, independent of pulmonary function before birth.

C. While surfactant has minor immune-modulatory functions, its primary role is not infection prevention. Other components like alveolar macrophages and immunoglobulins play a more significant role in pulmonary immune defense.

D. Fetal breathing movements are controlled by the central nervous system and are not driven by surfactant. These movements begin around week 20 and help condition respiratory muscles, but surfactant is not their initiator.

Take home points

• Surfactant reduces alveolar surface tension, preventing collapse during neonatal breathing.

• Type II alveolar cells begin surfactant production around week 20.

• Adequate surfactant levels are critical by week 34 to avoid respiratory distress syndrome.

• L/S ratio ≥2:1 indicates sufficient surfactant for postnatal respiration.

Teratogen exposure during the first trimester poses the highest risk for congenital anomalies due to organogenesis, which occurs between weeks 3 and 8 of gestation. Teratogens disrupt cellular differentiation, DNA synthesis, and tissue morphogenesis, resulting in structural or functional fetal defects. Common teratogens include retinoic acid, ACE inhibitors, valproic acid, alcohol, tobacco, radiation, and certain infections such as rubella and toxoplasmosis. Severity depends on dose, timing, and genetic susceptibility. Avoidance and early counseling are crucial. No safe threshold exists for many teratogens, and even brief exposure can lead to anomalies during this critical developmental period.

Rationale for correct answers

C. Educating on teratogen avoidance is the most critical nursing intervention in the first trimester. This is the peak window for organ development, so exposure to substances like alcohol, tobacco, certain medications, or infections can lead to major congenital anomalies. Timely education minimizes preventable teratogenic risk.

Rationale for incorrect answers

A. Administering corticosteroids is used in the second or third trimester, typically between 24 and 34 weeks, to promote fetal lung maturity in cases of preterm labor risk. It does not prevent congenital anomalies and is not a first trimester intervention.

B. Monitoring fundal height is not applicable in the first trimester because the uterus remains a pelvic organ until around 12 weeks. Fundal height measurements begin after 20 weeks gestation as a tool for tracking fetal growth, not anomaly prevention.

D. Performing Leopold’s maneuvers is relevant in the third trimester, typically after 28 weeks, to assess fetal position and presentation. It is unrelated to early congenital anomaly prevention and not useful in the first trimester.

Take home points

• Teratogen exposure in the first trimester can cause irreversible structural defects.

• Weeks 3–8 are the most critical for organogenesis and highest teratogenic risk.

• Nursing education on substance avoidance is essential during early prenatal visits.

• Not all common interventions are appropriate or effective in the first trimester.

Human chorionic gonadotropin (hCG) is a glycoprotein hormone produced by syncytiotrophoblasts of the developing placenta beginning around day 6–8 post-fertilization. Its primary role in early pregnancy is to maintain the corpus luteum, which in turn secretes progesterone to sustain the endometrial lining and prevent menstruation. hCG levels double every 48–72 hours in a viable early pregnancy, peaking around 100,000 mIU/mL by weeks 8–11, then gradually decline. Normal range at 4 weeks gestation is approximately 5–426 mIU/mL. hCG also promotes immune tolerance, supports placental growth, and is the basis for urine and serum pregnancy tests.

Rationale for correct answers

B. hCG maintains the corpus luteum during the first 8–10 weeks of pregnancy, ensuring continued secretion of progesterone, which is essential for maintaining the decidua and preventing uterine contraction. Without hCG support, the corpus luteum would regress and lead to pregnancy loss.

Rationale for incorrect answers

A. Fetal lung maturation is not influenced by hCG. This function is regulated by cortisol and surfactant production, which are stimulated by glucocorticoids such as betamethasone during the third trimester.

C. Fetal weight gain occurs primarily in the third trimester and is regulated by placental nutrient transfer, insulin-like growth factors, and maternal nutrition, not by hCG.

D. Labor contractions are initiated by increased oxytocin, prostaglandins, and estrogen at term. hCG has no role in triggering parturition.

Take home points

• hCG maintains corpus luteum function in early pregnancy to support progesterone production.

• Peak hCG levels occur between weeks 8–11 and decline thereafter.

• hCG is the hormone detected in pregnancy tests.

• It is produced by syncytiotrophoblast cells of the trophoblast.

Folic acid supplementation is critical for preventing neural tube defects (NTDs) such as spina bifida and anencephaly, which arise from failure of neural tube closure by day 28 post-conception. Folate, a B-vitamin (B9), is required for DNA synthesis, methylation, and cell division. Since neural tube formation occurs early, often before pregnancy is confirmed, supplementation should begin at least 1 month prior to conception. The recommended daily intake for women of childbearing age is 400 mcg (0.4 mg) of folic acid. For women with a history of NTDs or high-risk conditions (e.g., diabetes, antiseizure therapy), the dosage increases to 4 mg daily.

Rationale for correct answers

C. The CDC and WHO recommend 400 mcg of folic acid daily for all women of childbearing potential to reduce the risk of NTDs. This amount ensures adequate folate status for early embryonic neural tube closure, which completes by the 4th week of gestation.

Rationale for incorrect answers

A. 100 mcg is insufficient for NTD prevention. This dose may be found in food but is below the therapeutic threshold required for reducing neural tube malformations.

B. 200 mcg is still subtherapeutic. Evidence-based guidelines consistently show that at least 400 mcg per day is needed for effective neural tube defect risk reduction.

D. 800 mcg is above the general recommendation. While not harmful in most cases, this higher dose is reserved for special populations or prenatal supplements and is not routinely recommended for all women unless otherwise indicated.

Take home points

• The neural tube closes by day 28; early folic acid intake is essential.

• 400 mcg daily is recommended for all women of reproductive age.

• Higher doses are used in women with prior NTD-affected pregnancies or high-risk conditions.

• Folate is vital for DNA synthesis and embryonic cell division.

Fetal sexual differentiation begins early but genitalia visualization on imaging is influenced by several developmental milestones. Testosterone, secreted by fetal Leydig cells, influences external genitalia starting from week 8. However, distinct labioscrotal and phallus development features become ultrasonographically visible around week 14. The normal fetal heart rate is 110–160 bpm, and accurate sex determination depends on genital tubercle angle, with full differentiation by week 14. Chromosomal sex is determined at conception (XX or XY), but phenotypic differentiation requires hormonal influence, especially dihydrotestosterone.

Rationale for correct answers

D. By week 14, the external genitalia are typically developed enough to be distinguished by ultrasound. The scrotal sac and penile shaft in males, and labial folds in females, become distinct. Visualization accuracy improves with high-resolution transabdominal ultrasound and adequate amniotic fluid volume.

Rationale for incorrect answers

A. Week 8 marks the start of genital ridge differentiation into either testes or ovaries under influence of the SRY gene in XY embryos. However, external genitalia are still undifferentiated and identical in appearance in both sexes, making ultrasound distinction impossible.

B. By week 10, internal reproductive structures such as Müllerian and Wolffian ducts begin differentiating. However, external features remain ambiguous on imaging. At this stage, the genital tubercle is still forming and appears similar in both sexes.

C. Week 12 is the transitional phase where the external genitalia begin to show early signs of sexual differentiation. However, the features are often subtle, and accurate identification on ultrasound remains unreliable due to overlapping characteristics and suboptimal visualization.

Take home points

• Ultrasound visualization of external genitalia becomes reliable around week 14 of gestation.

• Phenotypic differentiation requires androgens such as testosterone and dihydrotestosterone.

• Chromosomal sex is determined at fertilization, but visible genitalia emerge later.

• Genital tubercle angle and shape are early markers but lack specificity before week 14.

Fetal renal development begins during week 5 of gestation with the formation of the metanephros, the permanent kidney. By week 9–12, the kidneys start producing urine, which is excreted into the amniotic cavity, making the kidneys a major contributor to amniotic fluid volume. Amniotic fluid, composed largely of fetal urine after the first trimester, is essential for lung development, fluid-electrolyte balance, and musculoskeletal movement. The fetal glomerular filtration rate (GFR) remains low compared to postnatal levels, and fetal kidneys do not filter maternal blood. Normal amniotic fluid index (AFI) ranges from 5 to 25 cm in the second and third trimesters.

Rationale for correct answers

B. By week 12, fetal kidneys begin producing urine, which is excreted into the amniotic sac. This urine significantly contributes to amniotic fluid volume, which is vital for normal fetal development, particularly pulmonary and musculoskeletal growth.

Rationale for incorrect answers

A. Red blood cells are produced by the yolk sac early in gestation, then by the liver and spleen. The fetal kidneys do not participate in hematopoiesis at any stage.

C. The fetal kidneys are immature and do not regulate systemic blood pressure effectively. Fetal blood pressure regulation is primarily under control of the placenta and fetal adrenal hormones, not the renal system.

D. Fetal kidneys do not filter maternal blood. Exchange of nutrients and waste products between mother and fetus occurs via the placenta, not through direct blood filtration by fetal organs.

Take home points

• Fetal kidneys begin producing urine by weeks 9–12.

• Urine becomes the main source of amniotic fluid after the first trimester.

• Amniotic fluid supports lung development and fetal movement.

• Fetal kidneys do not regulate blood pressure or filter maternal blood.

Placental function is central to fetal development, beginning after implantation and becoming fully functional by the end of the first trimester. The placenta serves as a semi-permeable barrier, allowing nutrient and gas exchange, waste elimination, and hormone production. It transfers oxygen, glucose, amino acids, and fatty acids to the fetus and removes carbon dioxide, urea, and other waste products. It also synthesizes essential hormones such as hCG, progesterone, estrogen, and human placental lactogen (hPL) to support pregnancy and fetal growth. While it offers partial immune protection, it does not fully block pathogens like rubella virus or Toxoplasma gondii.

Rationale for correct answers

C. The placenta facilitates bidirectional exchange of nutrients, oxygen, and waste between maternal and fetal circulations and produces hormones like hCG, progesterone, estrogen, and hPL, which are vital for maintaining pregnancy and supporting fetal development.

Rationale for incorrect answers

A. Fetal red blood cells are produced by the yolk sac, liver, and bone marrow during different stages of development, not the placenta. The placenta does not have a hematopoietic function.

B. Fetal temperature is regulated by maternal homeostasis, not by the placenta. The fetus remains slightly warmer (~0.5°C) than the maternal core temperature due to high metabolic activity.

D. While the placenta acts as a partial barrier, it does not prevent all infections. Pathogens such as cytomegalovirus, rubella, herpes simplex virus, varicella-zoster, HIV, and Toxoplasma gondii can cross the placenta and cause congenital infections.

Take home points

• The placenta is responsible for gas, nutrient, and waste exchange.

• It produces hCG, progesterone, estrogen, and hPL.

• It is not a site of red blood cell production.

• It offers limited protection against infections.

Fundal height measurement is a non-invasive clinical tool used to assess uterine growth and indirectly estimate fetal development. It is measured in centimeters from the pubic symphysis to the top of the uterine fundus. From weeks 18 to 32, the fundal height in centimeters typically equals the gestational age in weeks ±2 cm. Before 20 weeks, the uterus gradually rises through the abdomen. By 16 weeks, the fundus is typically located midway between the pubic symphysis and the umbilicus, and the expected measurement is approximately 14–18 cm.

Rationale for correct answers

B. At 16 weeks gestation, the uterus has ascended into the abdomen, and the expected fundal height is between 14 and 18 cm. This corresponds anatomically to a position halfway between the pubic symphysis and the umbilicus.

Rationale for incorrect answers

A. A fundal height of 8–10 cm is expected at approximately 12 weeks gestation, when the uterus is still just palpable above the pubic symphysis. At 16 weeks, this measurement would indicate uterine growth lag.

C. A measurement of 20–22 cm correlates with about 20–22 weeks gestation. At this point, the fundus is typically at the level of the umbilicus, not applicable to a 16-week pregnancy.

D. A fundal height of 24–26 cm is appropriate for 24–26 weeks gestation, when the fundus is well above the umbilicus. This would be significantly advanced for a 16-week pregnancy and may indicate incorrect dating or conditions like polyhydramnios.

Take home points

• Fundal height in cm generally matches gestational age in weeks between 18–32 weeks.

• At 16 weeks, fundal height should be 14–18 cm and located midway between symphysis and umbilicus.

• Lower-than-expected height may indicate fetal growth restriction or incorrect dating.

• Higher-than-expected height may suggest multiple gestation or polyhydramnios.

Fetal reflex development follows a specific neurological sequence and reflects central nervous system maturation. Between weeks 17–20, the sucking reflex becomes increasingly coordinated as the brainstem and cranial nerves mature. This reflex involves cranial nerves V (trigeminal), VII (facial), IX (glossopharyngeal), X (vagus), and XII (hypoglossal) and is essential for postnatal feeding. Fetal swallowing of amniotic fluid, observed on ultrasound, reflects functional development of oromotor coordination. Although sucking may begin as early as week 14, it becomes coordinated and repetitive by weeks 17–20, laying the foundation for effective breastfeeding after birth.

Rationale for correct answers

B. The sucking reflex becomes more coordinated between weeks 17–20 as cranial nerves responsible for oral motor function mature. This coordination is critical for future feeding and is often visualized on ultrasound as fetal swallowing or thumb-sucking behavior.

Rationale for incorrect answers

A. The grasping reflex appears later, typically after week 26, and becomes more pronounced in the third trimester. It involves finger flexion in response to stimulation and is mediated by spinal and cortical circuits.

C. The stepping reflex does not develop in utero. It emerges postnatally, around birth to 6 weeks, as a primitive response when the soles touch a flat surface.

D. The rooting reflex, which helps infants locate a nipple by turning the head toward stimuli on the cheek, begins developing in the third trimester and is generally seen postnatally at full term, not coordinated at 17–20 weeks.

Take home points

• The sucking reflex becomes coordinated by 17–20 weeks gestation.

• It is essential for postnatal feeding and involves multiple cranial nerves.

• Grasping and rooting reflexes appear later in gestation or after birth.

• Reflex development reflects CNS and cranial nerve maturation.

Fetal eyelid development follows a defined timeline that reflects neurological and anatomical maturation. The eyelids fuse by approximately week 10 to protect the developing eye and remain fused to allow for proper corneal and conjunctival differentiation. By around week 26, the eyelids separate, allowing the fetus to open and close the eyes in response to light and other stimuli. This milestone is associated with optic nerve myelination and increasing visual system activity, though vision remains immature. The retina is still developing, and light perception is limited. This separation coincides with increased blink-startle responses and maturation of REM-like eye movements.

Rationale for correct answers

B. Separation of the eyelids typically occurs by week 26, allowing the fetus to begin opening its eyes. This marks a significant milestone in fetal neurological and sensory development, including initiation of visual reflexes and responses to light.

Rationale for incorrect answers

A. Taste bud development begins much earlier, around weeks 7–8, and by week 14, taste receptors are already functional. While taste sensation continues to mature, this is not a unique milestone of week 26.

C. Formation of fingerprints (dermal ridges) is completed by weeks 17–19, during the second trimester. This unique feature arises due to genetic and intrauterine influences on skin patterning.

D. Complete lung maturation does not occur by week 26. Type II alveolar cells begin surfactant production around weeks 24–28, but full structural and functional lung maturity typically is not achieved until week 36–37.

Take home points

• Fetal eyelids fuse around week 10 and reopen by week 26.

• Eye opening indicates sensory and CNS maturation.

• Fingerprints form between weeks 17–19, earlier than eye opening.

• Lung maturation continues into late third trimester.

Leopold’s maneuvers are a systematic four-step abdominal palpation technique used during the second and third trimesters to assess fetal position, lie, and presentation. These maneuvers help determine the fundal content, fetal back location, presenting part, and engagement in the maternal pelvis. Performed after week 24, they become more reliable as the uterus enlarges and fetal parts are more palpable. Knowing fetal position assists in evaluating labor progression and identifying malpresentation (e.g., breech, transverse). Normal fetal lie is longitudinal, and cephalic presentation is most common by term.

Rationale for correct answers

B. Leopold’s maneuvers assess fetal lie (longitudinal or transverse), presentation (cephalic or breech), and position (e.g., left occiput anterior) by palpating the uterus systematically. At 28 weeks, this helps anticipate delivery planning and detect malpresentation.

Rationale for incorrect answers

A. Amniotic fluid volume is assessed via ultrasound, not by Leopold’s maneuvers. The amniotic fluid index (AFI) is measured in centimeters, with normal range between 5–25 cm during the second and third trimesters.

C. Fetal heart rate is evaluated using Doppler ultrasound or fetoscope, not palpation. Leopold’s maneuvers may assist in locating the best site for auscultation but do not measure heart rate directly.

D. Placental location is assessed by ultrasound imaging, particularly via transabdominal or transvaginal scan, especially to rule out conditions like placenta previa. Palpation cannot reliably locate the placenta.

Take home points

• Leopold’s maneuvers are palpation techniques used to assess fetal lie and presentation.

• They are most reliable after 24–28 weeks gestation.

• Amniotic fluid volume and placental location require ultrasound.

• Fetal heart rate is assessed using Doppler or fetoscope, not palpation.

Trophoblast function is central to early pregnancy, beginning immediately after blastocyst implantation. These cells differentiate into cytotrophoblasts and syncytiotrophoblasts, which invade the endometrial lining, allowing for implantation and formation of the placenta. Syncytiotrophoblasts secrete human chorionic gonadotropin (hCG), which supports the corpus luteum to maintain progesterone levels until placental steroidogenesis is established. Trophoblasts are not involved in surfactant production or neural development. Normal hCG levels in early pregnancy double approximately every 48–72 hours and peak around 100,000 mIU/mL by 10 weeks gestation.

Rationale for correct answers

A. Trophoblasts, specifically syncytiotrophoblasts, secrete hCG starting at implantation. hCG maintains the corpus luteum during early pregnancy, which secretes progesterone to support the endometrium.

B. Trophoblast cells give rise to the placenta, forming both fetal components such as the chorionic villi and contributing to maternal-fetal interface development.

E. Trophoblasts penetrate the endometrial epithelium, enabling implantation of the blastocyst. This process involves enzymatic digestion of maternal tissue and establishment of early uteroplacental circulation.

Rationale for incorrect answers

C. Surfactant is produced by type II alveolar cells in the fetal lungs starting around weeks 24–28, not by trophoblasts. It reduces surface tension in alveoli to aid postnatal lung expansion.

D. Neural tube closure is a function of the ectoderm, occurring around days 21–28 post-fertilization. Trophoblasts are extraembryonic cells and do not contribute to neuroectodermal development.

Take home points

• Trophoblasts facilitate implantation by invading maternal endometrium.

• They secrete hCG to maintain the corpus luteum and progesterone production.

• Trophoblasts form the fetal component of the placenta.

• They are not involved in neural or pulmonary development.

Neural tube defects (NTDs) are severe congenital malformations resulting from the incomplete closure of the neural tube during the third to fourth week of gestation, specifically between days 21–28. The most common forms include spina bifida, anencephaly, and encephalocele. NTDs are associated with several maternal and environmental risk factors. Folic acid deficiency impairs methylation and DNA synthesis, both critical for neural tube closure. Maternal diabetes, especially poorly controlled pregestational diabetes, increases oxidative stress and teratogenic risk. Anticonvulsant medications, such as valproic acid and carbamazepine, interfere with folate metabolism and increase NTD incidence. Normal folic acid supplementation is 400 mcg/day preconceptionally and in early pregnancy.

Rationale for correct answers

A. Maternal diabetes, particularly if poorly controlled, leads to increased oxidative stress and altered glucose metabolism, which disrupt early embryogenesis, including neural tube formation.

B. Folic acid deficiency is the most established risk factor for NTDs. Folate is vital for nucleotide synthesis and methylation. Low folate levels impair neural tube closure during early embryonic development.

D. Anticonvulsant medications, especially valproate and carbamazepine, are teratogenic due to their interference with folate metabolism, significantly increasing the risk for NTDs.

Rationale for incorrect answers

C. Excessive caffeine intake has not been definitively linked to neural tube defects. While high caffeine levels may be associated with other outcomes like miscarriage or low birth weight, they are not proven NTD risk factors.

E. Advanced maternal age increases the risk of chromosomal abnormalities such as trisomy 21, but it is not a direct risk factor for NTDs. NTD risk is more closely linked to nutritional and metabolic factors.

Take home points

• NTDs occur between days 21–28 of embryogenesis.

• Risk factors include folic acid deficiency, maternal diabetes, and certain anticonvulsants.

• Normal folic acid requirement is 400 mcg/day to prevent NTDs.

• Advanced age and caffeine are not primary contributors to NTDs.

Miscarriage (also called spontaneous abortion) is the loss of a pregnancy before 20 weeks of gestation, with most cases occurring in the first trimester (before 13 weeks). The most common cause is chromosomal abnormalities, followed by maternal conditions like thyroid disorders, infections, or uterine anomalies. Clinical signs include vaginal bleeding, abdominal cramping, and loss of pregnancy symptoms such as nausea and breast tenderness. Diagnosis is supported by ultrasound and quantitative hCG levels, which should double every 48–72 hours in a viable early pregnancy. A fetal heart rate is considered normal between 110–160 beats per minute.

Rationale for correct answers

A. Vaginal bleeding in the first trimester, especially when persistent or heavy, is a common sign of threatened or inevitable miscarriage. It may be accompanied by passage of clots or tissue.

B. Severe abdominal cramping or back pain is a hallmark of miscarriage due to uterine contractions and cervical dilation. It often intensifies as the pregnancy tissue is expelled.

D. Loss of pregnancy symptoms, such as resolution of nausea or breast soreness before the end of the first trimester, may indicate hormonal decline following embryonic demise.

Rationale for incorrect answers

C. Increased fundal height is not a sign of miscarriage. In fact, a decreasing or non-rising fundal height may be more indicative of pregnancy loss or intrauterine growth restriction.

E. A fetal heart rate of 140 beats per minute is within the normal range (110–160 bpm) and strongly indicates a viable pregnancy. Its presence rules out miscarriage at that moment.

Take home points

• First trimester miscarriage presents with bleeding, cramping, and loss of pregnancy symptoms.

• Chromosomal abnormalities are the most common cause.

• Normal fetal heart rate (110–160 bpm) rules out miscarriage.

• Miscarriage is confirmed by ultrasound and declining hCG levels.

Embryonic organogenesis occurs during weeks 3–8 of gestation, a period marked by rapid cellular differentiation, morphogenesis, and high vulnerability to teratogens. During this stage, the three germ layers—ectoderm, mesoderm, and endoderm—differentiate into major organ systems. The central nervous system forms from the ectoderm beginning with neural tube closure by day 28. The cardiovascular system is the first functional organ system, with the primitive heart beating by day 22. Limb buds appear by week 4, followed by elongation and digital separation. The digestive system originates from endoderm, with gut tube formation by week 4. The reproductive system, although genetically determined early, structurally differentiates later, during the fetal period.

Rationale for correct answers

A. The central nervous system begins developing early in the embryonic period. The neural plate forms in week 3, and the neural tube closes by week 4, initiating brain and spinal cord development.

B. The cardiovascular system starts forming in week 3. By day 22, the primitive heart tube begins beating and circulates blood, making it the earliest functioning organ system.

C. Limb buds become visible by week 4. By week 8, limb differentiation is advanced, including the formation of digits through programmed cell death (apoptosis) in the hand and foot plates.

D. The digestive system begins forming in week 4 from the endodermal germ layer. The primitive gut is divided into foregut, midgut, and hindgut, which later give rise to organs like the stomach, intestines, and liver.

Rationale for incorrect answers

E. The reproductive system, while genetically established at fertilization (XX or XY), begins structural differentiation later, primarily during the fetal period (after week 9). Gonadal development becomes histologically apparent between weeks 10–12.

Take home points

• Organogenesis occurs between weeks 3–8, known as the embryonic period.

• CNS, cardiovascular, digestive, and limb development all begin during this stage.

• The heart starts beating by day 22, making it the first functioning organ.

• Reproductive organs differentiate structurally later, during the fetal period.

Third trimester nursing care (weeks 28–40) centers on fetal maturation, maternal readiness for delivery, and monitoring for complications like preterm labor or infections. At this stage, the fetus undergoes rapid brain growth, lung surfactant production, and weight gain, reaching approximately 3,000–3,500 grams by term. Nurses must ensure Rho(D) immune globulin (RhoGAM) is administered at 28 weeks for Rh-negative mothers to prevent alloimmunization. Group B Streptococcus (GBS) screening is performed between 36–37 weeks. Preterm labor signs include uterine contractions, pelvic pressure, and cervical changes before 37 weeks. Fetal kick count education is essential, with fewer than 10 movements in 2 hours considered abnormal.

Rationale for correct answers

A. RhoGAM is administered at 28 weeks to Rh-negative mothers to prevent maternal antibody formation against Rh-positive fetal red blood cells, which can lead to hemolytic disease in future pregnancies.

B. Monitoring for preterm labor is critical during the third trimester. Early recognition of signs like uterine contractions every 10 minutes or cervical dilation enhances neonatal outcomes through timely interventions.

D. GBS screening is recommended at 36–37 weeks to identify maternal colonization. If positive, intrapartum antibiotics reduce the risk of neonatal GBS sepsis.

E. Educating mothers about fetal movement monitoring helps detect fetal distress. A common method is counting at least 10 movements in 2 hours; decreased movement may signal hypoxia.

Rationale for incorrect answers

C. Folic acid supplementation is essential preconceptionally and during the first trimester to prevent neural tube defects, which occur by day 28 of gestation. It is not a primary focus in the third trimester.

Take home points

• RhoGAM is given at 28 weeks to Rh-negative mothers to prevent alloimmunization.

• GBS screening occurs at 36–37 weeks to prevent neonatal infection.

• Preterm labor signs require immediate attention before 37 weeks.

• Kick counts help assess fetal well-being in late pregnancy.