Prenatal Care — MCQs

A 23-year-old female presents with a missed menstrual period of two cycles and a positive urine pregnancy test. Ultrasound confirms a 12-week gestation. She is concerned because she received the Measles Mumps Rubella (MMR) vaccine four months prior to conception, having been advised to wait three months before conceiving. The pregnancy is desired. What is the most appropriate next step?

Prenatal Care Indian Medical PG Practice Questions and MCQs

Question 361: Which of the following is NOT true about femur length used as a fetal biometric measure?

A. Femur length used for gestational age estimation has a variation of 7 to 11 days in the second trimester.
B. A shortened femur length suggests evaluation for skeletal dysplasia.
C. Femur length correlates well with both BPD and gestational age. (Correct Answer)
D. Femur length is measured excluding the epiphysis.

Explanation: **Explanation:** The correct answer is **C**. While Femur Length (FL) is a highly reliable parameter for estimating gestational age, it **does not correlate well with Biparietal Diameter (BPD)** in cases of growth restriction or certain anomalies. In conditions like Intrauterine Growth Restriction (IUGR), the BPD may be reduced (due to head sparing or compression), while the FL remains relatively preserved. Therefore, relying on a correlation between the two can lead to diagnostic errors. **Analysis of Options:** * **Option A:** In the second trimester (14–28 weeks), FL is a precise predictor of gestational age with a standard deviation of approximately **±7 to 11 days**. Its accuracy decreases in the third trimester (±3 weeks). * **Option B:** A femur length significantly below the 5th percentile (or <0.91 observed/expected ratio) is a soft marker for aneuploidy (Down syndrome) and a primary screening finding for **skeletal dysplasias** (e.g., Achondroplasia). * **Option C (Correct):** As explained, FL and BPD do not always correlate, especially in pathological states or late pregnancy. * **Option D:** For accurate measurement, the ultrasound beam should be perpendicular to the femoral shaft. The measurement must include the **entire ossified diaphysis** but strictly **exclude the cartilaginous epiphyses** (distal femoral epiphysis) to avoid overestimating age. **High-Yield Clinical Pearls for NEET-PG:** * **Best parameter for GA in 1st Trimester:** Crown-Rump Length (CRL) — most accurate overall (±3–5 days). * **Best parameter for GA in 2nd Trimester:** Head Circumference (HC). * **FL/AC Ratio:** Used to detect IUGR; a ratio >23.5 suggests growth restriction. * **Distal Femoral Epiphysis (DFE):** Its appearance on USG at **32 weeks** signifies fetal maturity.

Question 362: Which of the following fetal conditions results in low alpha-fetoprotein levels?

A. Anencephaly
B. Anterior abdominal wall defects
C. Renal anomalies
D. Down's syndrome (Correct Answer)

Explanation: **Explanation:** Alpha-fetoprotein (AFP) is a glycoprotein synthesized by the fetal yolk sac and later by the fetal liver. It is the fetal equivalent of albumin. Maternal Serum Alpha-Fetoprotein (MSAFP) levels are a crucial component of second-trimester screening (Triple/Quadruple markers). **1. Why Down’s Syndrome is Correct:** In pregnancies affected by **Down’s syndrome (Trisomy 21)**, the MSAFP levels are characteristically **decreased** (typically <0.5 MoM). While the exact pathophysiology is not fully understood, it is attributed to reduced fetal liver synthesis or a smaller-than-normal yolk sac. In a Quadruple screen for Down’s syndrome, remember the mnemonic **"HI" is High**: **H**CG and **I**nhibin-A are elevated, while AFP and Estriol (uE3) are low. **2. Why the Incorrect Options are Wrong:** Elevated AFP levels (typically >2.5 MoM) occur when there is a "leak" of fetal protein into the amniotic fluid or maternal circulation: * **Anencephaly:** Open Neural Tube Defects (NTDs) allow AFP to leak from the exposed fetal cerebrospinal fluid. * **Anterior Abdominal Wall Defects:** Conditions like Gastroschisis and Omphalocele result in direct exposure of fetal vessels/viscera to amniotic fluid, raising AFP. * **Renal Anomalies:** Congenital nephrotic syndrome (Finnish type) causes massive fetal proteinuria, leading to very high AFP levels. **3. High-Yield Clinical Pearls for NEET-PG:** * **Most common cause of an abnormal MSAFP:** Incorrect gestational dating (underestimation of age). * **Low AFP:** Down’s syndrome, Edward’s syndrome (Trisomy 18), Molar pregnancy, and Fetal macrosomia (due to dilution). * **High AFP:** NTDs, Multiple gestations, Abdominal wall defects, Renal anomalies, and Pilonidal cysts. * **Diagnostic Step:** If MSAFP is elevated, the next step is a **Targeted Ultrasound** to confirm dating and exclude structural anomalies.

Question 363: Information obtained by lateral plate X-ray pelvimetry includes all EXCEPT:

A. Sacral curve
B. True conjugate
C. Bispinous diameter (Correct Answer)
D. Inclination of the pelvis

Explanation: To understand this question, one must distinguish between the anatomical planes visualized in different radiographic views of the pelvis. **Why Bispinous Diameter is the Correct Answer:** The **bispinous diameter** (the distance between the two ischial spines) represents the narrowest part of the pelvic mid-cavity. This is a **transverse diameter**. On a **lateral plate X-ray**, the two ischial spines are superimposed on one another. Therefore, it is impossible to measure the horizontal distance between them. This diameter can only be measured using an anteroposterior (AP) view (specifically the Chassard-Lapiné view or Thoms' view). **Explanation of Incorrect Options:** The lateral view provides a profile of the pelvis, allowing for the measurement of sagittal (anteroposterior) diameters and the assessment of the posterior pelvic architecture: * **Sacral Curve:** The lateral view clearly shows the concavity or flatness of the sacrum, which is vital for assessing pelvic adequacy. * **True Conjugate:** This is the distance from the upper margin of the symphysis pubis to the sacral promontory. Since this is an AP diameter, it is easily measured on a lateral film. * **Inclination of the Pelvis:** This refers to the angle formed between the plane of the pelvic inlet and the horizontal plane, which is best visualized from the side. **NEET-PG High-Yield Pearls:** * **Obstetric Conjugate:** The most important diameter of the pelvic inlet; it is measured on a lateral X-ray by subtracting 1 cm from the True Conjugate. * **Intertuberous Diameter:** Another transverse diameter (of the outlet) that cannot be seen on a lateral X-ray. * **Clinical Note:** Radiographic pelvimetry is largely replaced by clinical assessment and MRI/CT in modern practice due to radiation concerns, but it remains a classic exam topic for understanding pelvic anatomy.

Question 364: The triple test for the diagnosis of Down's syndrome includes all of the following except?

A. beta-hCG
B. alpha-fetoprotein
C. Human placental lactogen (hPL) level (Correct Answer)
D. Serum estriol level

Explanation: The **Triple Test** is a second-trimester screening tool (performed between 15–20 weeks of gestation) used to assess the risk of chromosomal abnormalities, primarily Down syndrome (Trisomy 21), and neural tube defects. ### **Explanation of the Correct Answer** **C. Human placental lactogen (hPL) level:** This is the correct answer because hPL is **not** a component of the triple test. While hPL is produced by the placenta and reflects placental function, it does not serve as a reliable biomarker for screening fetal aneuploidies in the second trimester. ### **Analysis of Incorrect Options** The triple test consists of three specific maternal serum markers: * **A. beta-hCG:** In Down syndrome, maternal serum levels of hCG are characteristically **increased**. * **B. alpha-fetoprotein (MSAFP):** In Down syndrome, MSAFP levels are **decreased**. (Conversely, they are increased in open neural tube defects). * **D. Serum estriol (uE3):** Specifically unconjugated estriol, which is **decreased** in Down syndrome. ### **Clinical Pearls for NEET-PG** * **Quadruple Test:** If **Inhibin-A** is added to the triple test, it becomes the Quadruple Test. Inhibin-A levels are **increased** in Down syndrome. * **Memory Aid (Down Syndrome):** "HI" is High — **H**CG and **I**nhibin-A are elevated; the rest (AFP and uE3) are low. * **Edward Syndrome (Trisomy 18):** All markers (AFP, hCG, uE3) are typically **decreased**. * **Best Time:** Although it can be done from 15–22 weeks, the ideal window is **16–18 weeks**. * **Combined Test (First Trimester):** Includes PAPP-A (decreased), beta-hCG (increased), and Nuchal Translucency (NT) scan.

Question 365: What is the approximate fetal requirement of iron?

A. 100 mg
B. 200 mg
C. 300 mg
D. 400 mg (Correct Answer)

Explanation: **Explanation:** The total iron requirement during a singleton pregnancy is approximately **1000 mg**. This requirement is distributed among the fetus, the placenta, maternal red blood cell expansion, and obligatory losses. The **fetal requirement** specifically accounts for approximately **300–400 mg** of iron. This iron is actively transported across the placenta, primarily during the third trimester, to support fetal erythropoiesis and the creation of hepatic iron stores that the neonate will utilize during the first six months of life. **Analysis of Options:** * **Option D (400 mg):** This is the correct value for the iron utilized by the **fetus and placenta** (with the fetus taking the lion's share of ~300 mg). In standard textbooks like Williams Obstetrics, 300-400 mg is the cited range for fetal needs. * **Option A (100 mg):** This represents the approximate iron content of the **placenta** alone. * **Option B (200 mg):** This represents the **obligatory iron loss** (via excretion through skin, gut, and tracks) during pregnancy. * **Option C (300 mg):** While 300 mg is often cited as the fetal requirement, 400 mg is the more comprehensive figure often used in exams to include the feto-placental unit or the upper limit of fetal needs. **High-Yield NEET-PG Pearls:** * **Total Iron Requirement:** 1000 mg (300-400 mg for fetus/placenta, 500 mg for maternal RBC expansion, 200 mg for losses). * **Iron Absorption:** Increases significantly in the second and third trimesters. * **Daily Supplementation:** The Government of India (IFA tablets) recommends 100 mg elemental iron and 500 mcg folic acid for 180 days during pregnancy. * **Net Iron Savings:** Amenorrhea during pregnancy "saves" about 200-300 mg of iron that would have been lost through menstruation.

Question 366: Which of the following statements is FALSE regarding chorionic villus sampling?

A. Strongly associated with faciomandibular defects (Correct Answer)
B. Performed between 10-12 weeks of gestation
C. Rh immunoglobulin prophylaxis is necessary for Rh-negative mothers
D. Performed to diagnose genetic disorders

Explanation: **Explanation:** Chorionic Villus Sampling (CVS) is a prenatal diagnostic procedure used to obtain placental tissue for genetic analysis. **1. Why Option A is the False Statement:** While early CVS (performed **before 9 weeks** of gestation) has been associated with limb reduction defects and oromandibular-hypogenesis syndromes, it is **not "strongly associated"** with these defects when performed at the standard clinical timing. Modern practice ensures CVS is done after 10 weeks, making the risk of such anomalies extremely low (comparable to the baseline population risk). Therefore, stating it is "strongly associated" is clinically inaccurate. **2. Analysis of Other Options:** * **Option B:** The standard window for CVS is **10–13 weeks** (often cited as 10–12 weeks in exams). Performing it earlier increases the risk of limb defects, while performing it later is technically feasible but usually replaced by amniocentesis. * **Option C:** CVS is an invasive procedure that carries a risk of feto-maternal hemorrhage. Therefore, **Anti-D prophylaxis** is mandatory for all Rh-negative, non-sensitized women to prevent isoimmunization. * **Option D:** The primary indication for CVS is the **diagnosis of genetic and chromosomal disorders** (e.g., Down syndrome, Thalassemia) via karyotyping or DNA analysis. Note: It cannot diagnose Neural Tube Defects (NTDs), as that requires amniotic fluid AFP levels. **High-Yield Clinical Pearls for NEET-PG:** * **CVS vs. Amniocentesis:** CVS provides earlier results (1st trimester) but cannot detect NTDs. * **Procedure-related pregnancy loss:** Approximately 0.5–1%. * **Techniques:** Can be performed Transabdominally (most common) or Transcervically. * **Confined Placental Mosaicism:** A unique pitfall of CVS where chromosomal abnormalities are found in the placenta but not in the fetus.

Question 367: At what value for a one-hour glucose challenge test would you recommend a standard glucose tolerance test?

A. 120 mg/dL
B. 140 mg/dL (Correct Answer)
C. 150 mg/dL
D. 160 mg/dL

Explanation: **Explanation:** The screening for Gestational Diabetes Mellitus (GDM) typically follows a two-step approach. The first step is the **Glucose Challenge Test (GCT)**, which involves administering 50g of oral glucose regardless of the time of the last meal. 1. **Why 140 mg/dL is correct:** According to ACOG (American College of Obstetricians and Gynecologists) and standard obstetric guidelines, a plasma glucose value of **≥140 mg/dL (7.8 mmol/L)** measured one hour after the 50g load is considered a positive screen. This threshold identifies approximately 80% of women with GDM. If the GCT is positive, the patient must proceed to the diagnostic 3-hour 100g Oral Glucose Tolerance Test (OGTT). 2. **Analysis of Incorrect Options:** * **120 mg/dL:** This value is too low and would result in an excessive number of false positives, leading to unnecessary diagnostic testing. * **150 mg/dL:** While some clinicians use 130 or 135 mg/dL to increase sensitivity (detecting up to 90% of GDM cases), 150 mg/dL is too high as a starting threshold and would miss many cases of GDM. * **160 mg/dL:** This is significantly above the screening cutoff. However, it is worth noting that if a GCT value is **≥200 mg/dL**, GDM is often diagnosed directly without needing the second-step OGTT. **High-Yield Clinical Pearls for NEET-PG:** * **Timing:** Screening is routinely performed between **24–28 weeks** of gestation. * **DIPSI Guidelines (India):** In India, the DIPSI (Diabetes in Pregnancy Study Group India) criteria are often used. It uses a **75g glucose load**, and a 2-hour value **≥140 mg/dL** is diagnostic of GDM in a single step. * **High-Risk Patients:** If risk factors are present (e.g., obesity, previous GDM, family history), screening should be done at the **first prenatal visit**.

Question 368: At 15 weeks of gestation, what condition is associated with increased alpha-fetoprotein in amniotic fluid?

A. Intrauterine fetal demise (Correct Answer)
B. Down syndrome
C. Turner syndrome
D. Normal pregnancy

Explanation: **Explanation:** **Alpha-fetoprotein (AFP)** is a glycoprotein synthesized by the fetal yolk sac and later by the fetal liver. It is excreted into the fetal urine and subsequently enters the amniotic fluid. **1. Why Intrauterine Fetal Demise (IUFD) is correct:** In the event of fetal death, the integrity of the fetal skin and mucosal membranes is compromised due to maceration and autolysis. This leads to the massive leakage of fetal serum proteins, including AFP, into the amniotic fluid. Consequently, amniotic fluid AFP (AF-AFP) levels rise significantly. **2. Analysis of Incorrect Options:** * **Down Syndrome (Trisomy 21):** This condition is characteristically associated with **decreased** levels of maternal serum AFP (MSAFP) and AF-AFP. (Mnemonic: "Down is Down"). * **Turner Syndrome (45, XO):** Similar to Down syndrome, Turner syndrome is generally associated with **low** AFP levels, unless there is a co-existing cystic hygroma, which might cause a localized increase. * **Normal Pregnancy:** AFP levels follow a predictable curve, peaking in amniotic fluid at 13–15 weeks and then gradually declining. The levels in IUFD are pathologically elevated far beyond the normal range. **3. NEET-PG Clinical Pearls:** * **Elevated AFP:** Associated with Neural Tube Defects (NTDs) like Anencephaly and Spina Bifida, abdominal wall defects (Omphalocele, Gastroschisis), multiple gestations, and IUFD. * **Decreased AFP:** Associated with Trisomy 21 (Down syndrome), Trisomy 18 (Edwards syndrome), and gestational trophoblastic disease. * **Confirmatory Test:** If AF-AFP is elevated, **Acetylcholinesterase (AChE)** levels are measured in the amniotic fluid to confirm an open neural tube defect.

Question 369: At what gestational age should maternal serum alpha-fetoprotein (MSAFP) levels typically be measured?

A. 9 weeks
B. 11 weeks
C. 15 weeks (Correct Answer)
D. 20 weeks

Explanation: **Explanation:** **Maternal Serum Alpha-Fetoprotein (MSAFP)** is a screening test used primarily to detect **Open Neural Tube Defects (ONTDs)** such as anencephaly and spina bifida. 1. **Why 15 weeks is correct:** The optimal window for measuring MSAFP is between **15 and 20 weeks** of gestation (the second trimester). While it can be measured throughout this period, the peak sensitivity for screening is generally between **16 and 18 weeks**. At 15 weeks, the levels are sufficiently elevated in the maternal circulation to provide a reliable baseline for screening. 2. **Why other options are incorrect:** * **9 & 11 weeks (Options A & B):** These are in the first trimester. During this time, MSAFP levels are too low to be diagnostic for neural tube defects. First-trimester screening typically focuses on PAPP-A and β-hCG for chromosomal anomalies (e.g., Down Syndrome). * **20 weeks (Option D):** While 20 weeks is the upper limit for MSAFP screening, it is less ideal because if an abnormality is detected, there is very little time left for follow-up diagnostic tests (like amniocentesis) and counseling before the legal limit for medical termination of pregnancy (MTP) in many regions. **High-Yield Clinical Pearls for NEET-PG:** * **Elevated MSAFP (>2.5 MoM):** Associated with ONTDs, abdominal wall defects (Omphalocele, Gastroschisis), multiple gestations, and fetal demise. The **most common cause** of an elevated MSAFP is **underestimation of gestational age** (dating error). * **Decreased MSAFP:** Associated with Trisomy 21 (Down Syndrome), Trisomy 18 (Edwards Syndrome), and molar pregnancy. * **Triple Test:** Includes MSAFP, hCG, and Estriol ($uE_3$). * **Quadruple Test:** Adds Inhibin-A to the Triple Test (performed between 15-20 weeks).

Question 370: A 23-year-old female presents with a missed menstrual period of two cycles and a positive urine pregnancy test. Ultrasound confirms a 12-week gestation. She is concerned because she received the Measles Mumps Rubella (MMR) vaccine four months prior to conception, having been advised to wait three months before conceiving. The pregnancy is desired. What is the most appropriate next step?

A. The risk associated with the MMR vaccine is minimal and not a sufficient reason to terminate the pregnancy. (Correct Answer)
B. The risk associated with the MMR vaccine is nil, and termination is inappropriate.
C. The risk associated with the MMR vaccine is high, and termination should be strongly considered.
D. The risk associated with the MMR vaccine is high, and termination is mandated.

Explanation: ### Explanation **1. Why Option A is Correct:** The MMR vaccine is a **live-attenuated vaccine**. Theoretically, there is a risk that the vaccine virus could cross the placenta and cause Congenital Rubella Syndrome (CRS). However, extensive clinical data and registries (such as those from the CDC) have shown **zero confirmed cases of CRS** in infants born to women who were inadvertently vaccinated shortly before or during pregnancy. While guidelines (like RCOG and CDC) recommend avoiding pregnancy for **28 days (1 month)** after MMR vaccination as a precaution, the actual observed risk is negligible. Therefore, accidental vaccination or conception shortly after vaccination is **not** an indication for termination of pregnancy. **2. Why Other Options are Incorrect:** * **Option B:** In medicine, the risk is rarely "nil." While no cases of CRS have been documented, the theoretical risk of live virus transmission exists. * **Options C & D:** These are factually incorrect. The risk is not "high." Suggesting or mandating termination based on MMR vaccination is against standard obstetric guidelines and evidence-based practice. **3. NEET-PG High-Yield Pearls:** * **Wait Period:** The current recommendation for the interval between MMR vaccination and conception is **1 month (28 days)**, though older guidelines suggested 3 months. * **Contraindicated Vaccines in Pregnancy:** Live vaccines are generally contraindicated. These include **MMR, Varicella, BCG, and Yellow Fever** (though Yellow Fever may be given if the risk of disease outweighs the risk of the vaccine). * **Safe Vaccines in Pregnancy:** Inactivated/Killed vaccines and Toxoids are safe. **Tetanus, Diphtheria, and Pertussis (Tdap)** and **Inactivated Influenza** are routinely recommended. * **Postpartum Vaccination:** If a woman is found to be rubella non-immune during pregnancy, the MMR vaccine should be administered in the **immediate postpartum period**. It is safe during breastfeeding.

Practice by Chapter

Preconception Counseling

Practice Questions

Pregnancy Diagnosis and Dating

Practice Questions

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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