Prenatal Care — MCQs

A 32-year-old G3P20L2 presents to the obstetrician's office for a routine OB visit at 30 weeks gestation. She has had no complications during the pregnancy and has had regular prenatal care. Her gestational age is confirmed with a first-trimester sonogram. During the routine OB visit, the fundal height measures 35 cm. All of the following can explain the size-date discrepancy except?

Q86Easy

Fetal length is affected if the mother has undernutrition during which period of gestation?

Q87Medium

What is the recommended daily dose of folic acid for a pregnant woman in the first trimester with a history of neural tube defects (NTD)?

Q88Medium

A high level of hCG is seen in all of the following conditions EXCEPT:

Q89Medium

A 18-week pregnant multigravida, Rh-negative, with a previous child born with a chromosomal abnormality, underwent cordocentesis. Which test is used to differentiate between maternal and fetal blood in a given sample?

Q90Medium

Which of the following is true about chorionic villi biopsy?

Prenatal Care Indian Medical PG Practice Questions and MCQs

Question 81: As an isolated finding, which of the following is associated with the highest risk of Down syndrome?

A. Increased nuchal fold thickness (Correct Answer)
B. Shortened femur
C. Absence of nasal bone
D. Echogenic bowel

Explanation: **Explanation:** In the second-trimester genetic sonogram (15–20 weeks), "soft markers" are used to adjust the age-related risk of Trisomy 21. While several markers exist, **increased nuchal fold thickness (≥6 mm)** is considered the most sensitive and specific isolated soft marker for Down syndrome. **1. Why Nuchal Fold is the Correct Answer:** The nuchal fold (measured in the second trimester) has the highest **Likelihood Ratio (LR)** among isolated findings, ranging from 11 to 17. An isolated thickened nuchal fold significantly increases the post-test probability of Down syndrome compared to other markers. It represents subcutaneous edema at the back of the fetal neck and is distinct from the first-trimester nuchal translucency (NT). **2. Analysis of Incorrect Options:** * **Absence of Nasal Bone (Option C):** While a powerful marker in the *first trimester* (high LR), its significance as an *isolated* finding in the second trimester is slightly lower than nuchal fold thickness in many screening algorithms, though it remains a strong marker. * **Shortened Femur (Option B):** This has a low LR (approx. 1.5–2.5) when found in isolation. It is often a constitutional finding or associated with skeletal dysplasias and FGR rather than being highly specific for Down syndrome. * **Echogenic Bowel (Option D):** This carries an LR of approximately 6. While significant, it is also associated with cystic fibrosis, CMV infection, and intra-amniotic hemorrhage, making it less specific for Trisomy 21 than a thickened nuchal fold. **Clinical Pearls for NEET-PG:** * **Nuchal Translucency (NT):** Measured at 11–13+6 weeks. >3.5 mm is the threshold for increased risk. * **Nuchal Fold (NF):** Measured at 15–20 weeks. **≥6 mm** is the pathological cutoff. * **Most common sonographic finding** in Down syndrome is actually **no abnormality** (up to 70% of cases). * **Combined Screening (First Trimester):** NT + PAPP-A + free β-hCG (Detection rate ~85-90%).

Question 82: Myelodysplasia in a fetus can be best diagnosed by which of the following methods?

A. Alpha-fetoprotein (AFP) (Correct Answer)
B. Lumbar puncture
C. Human chorionic gonadotropin (HCG)
D. Unconjugated estriol

Explanation: **Explanation:** **1. Why Alpha-fetoprotein (AFP) is correct:** Myelodysplasia (a form of Neural Tube Defect or NTD) involves a failure of the neural tube to close properly. When the neural tube remains open, fetal serum proteins—primarily **Alpha-fetoprotein (AFP)**—leak directly into the amniotic fluid and subsequently cross into the maternal circulation. Maternal Serum AFP (MSAFP) is the primary screening tool used between 15–20 weeks of gestation. A significant elevation (typically >2.5 MoM) suggests an open NTD, such as myelomeningocele or anencephaly. **2. Why the other options are incorrect:** * **B. Lumbar puncture:** This is an invasive procedure used to sample cerebrospinal fluid in postnatal patients. It is not a prenatal diagnostic tool for fetal structural anomalies and carries significant risk to the fetus. * **C. Human chorionic gonadotropin (HCG):** While HCG is part of the "Triple" or "Quadruple" screen, it is primarily used to screen for **Aneuploidies** (e.g., Trisomy 21, where HCG is elevated). It is not a specific marker for neural tube defects. * **D. Unconjugated estriol (uE3):** Similar to HCG, uE3 is used in screening for chromosomal abnormalities. In Trisomy 21 and Trisomy 18, uE3 levels are typically decreased. It does not provide diagnostic value for myelodysplasia. **3. Clinical Pearls for NEET-PG:** * **Confirmatory Test:** If MSAFP is high, the next step is a targeted **Level II Ultrasound**. If the diagnosis remains uncertain, amniocentesis is performed to check for **Amniotic Fluid AFP** and **Acetylcholinesterase (AChE)**. AChE is the most specific marker for open NTDs. * **False Positives:** The most common cause of an elevated MSAFP is **incorrect gestational age** (under-dating). Other causes include multiple gestations and abdominal wall defects (omphalocele/gastroschisis). * **Prevention:** Pre-conceptional intake of **400 mcg of Folic Acid** (5 mg for high-risk cases) significantly reduces the incidence of NTDs.

Question 83: Amniocentesis is done for all of the mentioned indications EXCEPT?

A. Fetal lung maturity
B. Oligohydramnios (Correct Answer)
C. Congenital infections
D. Genetic defects

Explanation: **Explanation:** Amniocentesis is a procedure where amniotic fluid is aspirated from the gravid uterus for diagnostic or therapeutic purposes. The correct answer is **Oligohydramnios** because it is a **contraindication** (or a technical limitation) rather than an indication. 1. **Why Oligohydramnios is the Correct Answer:** Amniocentesis requires an adequate pocket of amniotic fluid to safely insert the needle without injuring the fetus or the umbilical cord. In oligohydramnios (decreased fluid volume), the risk of fetal injury and "dry tap" (failure to obtain fluid) is significantly high. In fact, amniocentesis is often used to *treat* polyhydramnios (therapeutic amnioreduction), not oligohydramnios. 2. **Analysis of Other Options:** * **Fetal Lung Maturity:** Historically, the L/S ratio (Lecithin/Sphingomyelin) and Phosphatidylglycerol levels were measured via amniocentesis to assess lung maturity before elective preterm delivery. * **Congenital Infections:** Amniotic fluid PCR is the gold standard for diagnosing intrauterine infections like TORCH (especially CMV and Toxoplasmosis). * **Genetic Defects:** This is the most common indication. Amniotic fluid contains desquamated fetal cells (amniocytes) used for karyotyping, FISH, and chromosomal microarray to detect Down syndrome and other aneuploidies. **NEET-PG High-Yield Pearls:** * **Timing:** Ideally performed between **15–20 weeks** of gestation. * **Early Amniocentesis:** Done between 12–14 weeks; however, it is associated with a higher risk of clubfoot (talipes equinovarus) and procedure loss. * **Risk of Fetal Loss:** Approximately 0.5% (1 in 200). * **Rh-Negative Mothers:** Always administer Anti-D immunoglobulin after the procedure to prevent isoimmunization.

Question 84: What is the appropriate treatment for a woman experiencing edema during pregnancy?

A. Salt restriction
B. Fluid restriction
C. Diuretics
D. Bed rest (Correct Answer)

Explanation: **Explanation:** Edema is a common physiological occurrence in pregnancy, affecting nearly 80% of healthy women. It primarily occurs due to the compression of the inferior vena cava by the gravid uterus, leading to increased venous pressure in the lower extremities, alongside pregnancy-induced sodium and water retention. **Why Bed Rest is Correct:** The most appropriate management for physiological edema is **bed rest in the left lateral position**. This position displaces the uterus from the inferior vena cava, enhancing venous return to the heart and increasing renal perfusion. Improved renal blood flow promotes natural diuresis, thereby reducing dependent edema. **Analysis of Incorrect Options:** * **Salt Restriction (A):** Unlike non-pregnant patients with hypertension, salt restriction is not recommended in pregnancy. Pregnant women require adequate sodium to maintain the necessary expansion of plasma volume. * **Fluid Restriction (B):** Restricting fluids is counterproductive and dangerous. Adequate hydration is essential to maintain uteroplacental perfusion and prevent urinary tract infections. * **Diuretics (C):** Diuretics are generally contraindicated for simple pregnancy edema. They can lead to a sudden decrease in plasma volume, potentially compromising placental blood flow and causing fetal growth restriction. They are reserved only for pathological conditions like pulmonary edema or congestive heart failure. **High-Yield Clinical Pearls for NEET-PG:** * **Physiological vs. Pathological:** Edema is considered physiological if it is limited to the ankles and disappears after a night’s rest. If edema is persistent, involves the face/hands, or is associated with hypertension and proteinuria, suspect **Preeclampsia**. * **Positioning:** The left lateral position is the "gold standard" for improving hemodynamics in pregnancy. * **Weight Gain:** Sudden excessive weight gain (e.g., >0.5 kg/week) is often the first sign of pathological edema before it becomes clinically visible.

Question 85: A 32-year-old G3P20L2 presents to the obstetrician's office for a routine OB visit at 30 weeks gestation. She has had no complications during the pregnancy and has had regular prenatal care. Her gestational age is confirmed with a first-trimester sonogram. During the routine OB visit, the fundal height measures 35 cm. All of the following can explain the size-date discrepancy except?

A. The 5-cm difference is within the error for fundal height measurements (Correct Answer)
B. Leiomyomas
C. Polyhydramnios
D. Fetal macrosomia

Explanation: ### Explanation **Concept:** Fundal height (Symphysio-fundal height or SFH) is a screening tool used to monitor fetal growth and amniotic fluid volume. Between **20 and 36 weeks** of gestation, the SFH in centimeters should ideally correspond to the gestational age in weeks, with an allowable variation of **± 2 cm**. #### Why Option A is the Correct Answer (The "Except") A fundal height of 35 cm at 30 weeks gestation represents a **5-cm discrepancy**. This exceeds the standard clinical margin of error (± 2 cm). Therefore, a 5-cm difference is considered clinically significant and warrants further investigation (usually via ultrasound) to rule out underlying pathology. It cannot be dismissed as a simple measurement error. #### Why the Other Options are Incorrect (Causes of "Size > Dates") These conditions characteristically cause the uterus to feel larger than expected for the gestational age: * **Leiomyomas (Fibroids):** Pre-existing uterine fibroids can enlarge during pregnancy due to estrogen stimulation, physically increasing the uterine volume and fundal height. * **Polyhydramnios:** An excessive volume of amniotic fluid distends the uterus beyond the expected size for the fetal age. * **Fetal Macrosomia:** A fetus that is large for gestational age (e.g., due to maternal diabetes or genetics) will naturally result in a higher SFH. --- ### High-Yield Clinical Pearls for NEET-PG * **The Rule of Thumb:** SFH (cm) = Gestational age (weeks) between 20–36 weeks. * **Discrepancy Threshold:** A difference of **>2 cm** (or >3 cm by some guidelines) is the trigger for an ultrasound to assess fetal growth (IUGR vs. Macrosomia) and Amniotic Fluid Index (AFI). * **Common Causes of Size > Dates:** Multiple pregnancy, Polyhydramnios, Macrosomia, Hydatidiform mole (early pregnancy), and pelvic masses like fibroids. * **Common Causes of Size < Dates:** Intrauterine Growth Restriction (IUGR), Oligohydramnios, and fetal transverse lie. * **Bladder Status:** Always ensure the patient has an empty bladder before measuring SFH to avoid false elevations.

Question 86: Fetal length is affected if the mother has undernutrition during which period of gestation?

A. First trimester
B. Second trimester
C. Third trimester
D. Any time during the pregnancy (Correct Answer)

Explanation: **Explanation:** The correct answer is **D. Any time during the pregnancy.** **Medical Concept:** Fetal growth is a continuous process characterized by three distinct cellular phases: **Hyperplasia** (increase in cell number), **Hypertrophy** (increase in cell size), and a combined phase. 1. **First Trimester:** Growth is primarily via cellular hyperplasia. Undernutrition here leads to a decrease in the total number of cells, resulting in overall growth restriction. 2. **Second Trimester:** Growth involves both hyperplasia and hypertrophy. 3. **Third Trimester:** Growth is predominantly via cellular hypertrophy and fat deposition. Since fetal length (linear growth) and weight are cumulative results of these processes, severe maternal undernutrition at **any stage** of gestation can impair the specific cellular activity occurring at that time, ultimately affecting the final fetal length. **Analysis of Incorrect Options:** * **A, B, and C:** While the *rate* of growth varies (weight gain is maximal in the third trimester, while linear growth is rapid in the second), nutritional insults are not restricted to a specific window. Restricting the answer to a single trimester ignores the fact that the skeletal template is formed early and elongated continuously. **High-Yield Clinical Pearls for NEET-PG:** * **Symmetric IUGR:** Caused by factors acting early in pregnancy (e.g., chromosomal anomalies, early infections, or severe early undernutrition). Both head and body are proportionately small. * **Asymmetric IUGR:** Usually caused by placental insufficiency in the **third trimester**. The head is spared (Brain Sparing Effect), but the abdominal circumference is reduced. * **Ponderal Index:** Used to differentiate between symmetric and asymmetric IUGR. * **Most sensitive parameter** for detecting IUGR on ultrasound is the **Abdominal Circumference (AC)**.

Question 87: What is the recommended daily dose of folic acid for a pregnant woman in the first trimester with a history of neural tube defects (NTD)?

A. 100 micrograms
B. 400 micrograms
C. 4 mg (Correct Answer)
D. 5 mg

Explanation: **Explanation:** The primary goal of periconceptional folic acid supplementation is to prevent **Neural Tube Defects (NTDs)**, such as anencephaly and spina bifida. Folic acid is essential for DNA synthesis and the closure of the neural tube, which occurs by the 28th day of gestation. **Why 4 mg is correct:** For women at **high risk**—specifically those with a **previous history** of a child affected by an NTD—the recurrence risk is significantly higher (approx. 2-3%). Clinical trials (notably the MRC Vitamin Study) established that a high dose of **4 mg (4000 mcg)** daily, starting at least 1-3 months prior to conception and continuing through the first trimester, reduces the risk of recurrence by over 70%. **Analysis of Incorrect Options:** * **A (100 mcg):** This is the dose typically found in standard multivitamins or the minimum requirement in some low-risk settings, but it is insufficient for preventing NTDs. * **B (400 mcg / 0.4 mg):** This is the standard recommended dose for **low-risk** (routine) pregnancies to prevent the first occurrence (primary prevention) of NTDs. * **D (5 mg):** While 5 mg is the standard tablet size available in many countries (including India) and is often prescribed for high-risk cases for practical reasons, the **evidence-based recommended dose** cited in standard textbooks (Williams Obstetrics) and guidelines for history-based high risk is specifically **4 mg**. **High-Yield Clinical Pearls for NEET-PG:** * **Timing:** Supplementation must begin **pre-conceptionally** because the neural tube closes before most women realize they are pregnant (Day 21–28). * **High-Risk Categories (Requiring 4-5 mg):** Previous child with NTD, parent with NTD, women on anti-epileptic drugs (Valproate, Carbamazepine), and women with BMI >35 or pre-gestational diabetes. * **Routine Dose:** 400 mcg (0.4 mg) for all women of reproductive age. * **Anemia Prevention:** Under the Anemia Mukt Bharat guidelines, pregnant women receive **60 mg elemental iron + 500 mcg (0.5 mg) folic acid** daily for 180 days starting from the second trimester.

Question 88: A high level of hCG is seen in all of the following conditions EXCEPT:

A. Down syndrome
B. Neural tube defect (Correct Answer)
C. Germ cell tumor
D. Gestational trophoblastic disease

Explanation: **Explanation:** Human Chorionic Gonadotropin (hCG) is a glycoprotein hormone produced by the syncytiotrophoblast. Understanding its variations is crucial for prenatal screening and oncology. **Why Neural Tube Defects (NTDs) is the correct answer:** In cases of **Neural Tube Defects** (like anencephaly or spina bifida), the primary biochemical marker that increases is **Alpha-Fetoprotein (AFP)**, due to leakage from the exposed fetal tissues. hCG levels typically remain **normal** in isolated NTDs. Therefore, it is the "except" in this list. **Analysis of Incorrect Options:** * **Down Syndrome (Trisomy 21):** In the second-trimester quadruple screen, Down syndrome is characterized by **elevated hCG** and Inhibin-A, while AFP and unconjugated Estriol (uE3) are decreased (Mnemonic: **HI**gh for **H**CG and **I**nhibin). * **Gestational Trophoblastic Disease (GTD):** Conditions like Hydatidiform mole involve massive proliferation of trophoblastic tissue, leading to **extremely high levels of hCG** (often >100,000 mIU/mL). * **Germ Cell Tumors:** Certain ovarian or testicular germ cell tumors, specifically **Choriocarcinomas** and some Dysgerminomas/Embryonal carcinomas, secrete hCG as a tumor marker. **High-Yield NEET-PG Pearls:** * **Low hCG levels** are associated with: Ectopic pregnancy (lower than expected for gestational age), threatened abortion, and Edwards syndrome (Trisomy 18). * **High hCG levels** are also seen in: Multiple pregnancies and Rh isoimmunization (due to placental hydrops). * **AFP** is the marker of choice for NTDs; it is **decreased** in Down syndrome.

Question 89: A 18-week pregnant multigravida, Rh-negative, with a previous child born with a chromosomal abnormality, underwent cordocentesis. Which test is used to differentiate between maternal and fetal blood in a given sample?

A. Kleihauer-Betke test
B. Apt test (Correct Answer)
C. Osmotic fragility test
D. Bubble stability test

Explanation: **Explanation:** The correct answer is the **Apt test** (Alkali Denaturation Test). This test is specifically designed to differentiate between fetal and maternal blood based on the biochemical properties of hemoglobin. **1. Why the Apt test is correct:** Fetal hemoglobin (**HbF**) is resistant to denaturation by strong bases, whereas adult hemoglobin (**HbA**) is not. In this test, the blood sample is mixed with 1% sodium hydroxide (NaOH). If the blood is maternal (HbA), it denatures and turns **yellow-brown**. If the blood is fetal (HbF), it remains stable and stays **pink**. This is crucial during cordocentesis to ensure the sample obtained is truly fetal blood and not contaminated by maternal blood. **2. Why the other options are incorrect:** * **Kleihauer-Betke test:** This is used to **quantify** the amount of fetal-maternal hemorrhage (FMH) in the maternal circulation (e.g., to calculate the dose of Anti-D). It is an acid-elution test performed on a maternal blood smear, not a direct test to identify the source of a sample. * **Osmotic fragility test:** Used primarily to diagnose **Hereditary Spherocytosis** by measuring the resistance of RBCs to hemolysis in hypotonic solutions. * **Bubble stability test:** A bedside test used to assess **fetal lung maturity** by checking for the presence of surfactants in amniotic fluid. **Clinical Pearls for NEET-PG:** * **Apt Test Uses:** Differentiating fetal from maternal blood in cases of **Vasa Previa** (vaginal bleeding) or during **Cordocentesis**. * **Cordocentesis (PUBS):** Usually performed after 18 weeks; the most common site is the umbilical vein at the placental insertion. * **Kleihauer-Betke Formula:** Fetal cells counted / Total cells × 5000 = Volume of FMH (mL). This is a high-yield calculation for Rh-isoimmunization questions.

Question 90: Which of the following is true about chorionic villi biopsy?

A. Strongly associated with fetal limb defects
B. Done between 10-12 weeks of gestation
C. Rh immunoglobulin prophylaxis is not necessary (Correct Answer)
D. Done to diagnose genetic disorders

Explanation: ### Explanation **Correct Answer: C. Rh immunoglobulin prophylaxis is not necessary** *(Note: There appears to be a discrepancy in the provided key. In standard clinical practice and for NEET-PG, Rh prophylaxis **is required** after CVS. However, if this specific question follows a specific controversial source or "except" logic, the medical fact remains: CVS is an invasive procedure that carries a risk of feto-maternal hemorrhage. Therefore, Rh-negative unsensitized women **must** receive Anti-D immunoglobulin.)* **Why the other options are evaluated:** * **Option A (Limb Defects):** While early studies suggested a link between CVS and limb reduction defects (Oromandibular limb hypogenesis), this is primarily associated with procedures done **before 9 weeks**. When performed after 10 weeks by experienced hands, the risk is negligible. * **Option B (Timing):** CVS is typically performed between **10–13 weeks** of gestation. While "10-12 weeks" is close, the standard window extends to 13 weeks. (In many exams, if multiple options are plausible, the most "clinically absolute" fact is tested). * **Option D (Diagnosis):** CVS is indeed used to diagnose genetic and metabolic disorders. However, it **cannot** diagnose neural tube defects (NTDs) because it does not measure Alpha-fetoprotein (AFP), unlike amniocentesis. **High-Yield Clinical Pearls for NEET-PG:** 1. **CVS vs. Amniocentesis:** CVS provides earlier results (1st trimester) but carries a slightly higher miscarriage risk (~0.5–1%) and cannot detect NTDs. 2. **Confined Placental Mosaicism:** A unique complication of CVS where the placenta has a different chromosomal makeup than the fetus, potentially leading to false positives. 3. **Contraindications:** Active vaginal infection (for transcervical route) or multiple gestations (relative). 4. **Anti-D Prophylaxis:** Always remember the "Invasive Procedure Rule"—any procedure that can cause feto-maternal hemorrhage (CVS, Amniocentesis, Cordocentesis) requires 50–300 mcg of Anti-D in Rh-negative mothers.

Practice by Chapter

Preconception Counseling

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Pregnancy Diagnosis and Dating

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Routine Antenatal Assessments

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Maternal Physiological Changes

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Nutrition in Pregnancy

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Screening Tests in Pregnancy

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Fetal Growth Assessment

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High-Risk Pregnancy Identification

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Antenatal Complications Management

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Psychosocial Aspects of Pregnancy

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