Endocrinology of Pregnancy — MCQs

Endocrinology of Pregnancy Indian Medical PG Practice Questions and MCQs

Question 41: What change occurs in the resistance of the uteroplacental vasculature during pregnancy?

A. Low resistance to high resistance.
B. High resistance to low resistance. (Correct Answer)
C. No change in resistance.
D. Resistance varies unpredictably.

Explanation: ### Explanation The correct answer is **B. High resistance to low resistance.** **1. Why it is correct:** In a non-pregnant state, the uterine arteries are high-resistance vessels. During pregnancy, the demand for blood flow to the fetus increases significantly (from ~50 mL/min to ~600–700 mL/min). To accommodate this, a process called **trophoblastic invasion** occurs. Cytotrophoblasts invade the maternal **spiral arteries**, replacing the muscular and elastic layers with fibrinoid material. This transforms narrow, high-resistance vessels into dilated, tortuous, **low-resistance channels**. This physiological adaptation ensures a continuous, high-volume blood supply to the intervillous space, independent of maternal vasoconstrictive stimuli. **2. Why the other options are wrong:** * **Option A:** Low to high resistance would cause fetal growth restriction and ischemia. This is the pathological state seen in preeclampsia, not normal pregnancy. * **Option C:** If resistance did not change, the uterine blood flow could not increase 10–15 fold, leading to placental insufficiency. * **Option D:** The change is highly predictable and essential for a viable pregnancy; it is a hallmark of normal placentation. **3. High-Yield Clinical Pearls for NEET-PG:** * **Waveform Change:** On Doppler ultrasound, this transition is marked by the **disappearance of the diastolic notch** in the uterine artery by 20–24 weeks. * **Preeclampsia Connection:** Failure of the second wave of trophoblastic invasion (which involves the intramyometrial portion of spiral arteries) leads to persistent high resistance, resulting in **Preeclampsia** and **IUGR**. * **Refractoriness:** During pregnancy, the uteroplacental vasculature becomes refractory to the pressor effects of **Angiotensin II**, further maintaining the low-resistance state.

Question 42: Which hormone is essential for the salvage of the corpus luteum?

A. hCG (Correct Answer)
B. FSH
C. AFP
D. Estrogen

Explanation: **Explanation:** The correct answer is **hCG (human Chorionic Gonadotropin)**. **1. Why hCG is correct:** In a normal menstrual cycle, the corpus luteum (CL) has a finite lifespan of about 14 days, after which it degenerates (luteolysis), leading to a drop in progesterone and the onset of menstruation. However, if fertilization occurs, the syncytiotrophoblast of the developing blastocyst begins secreting **hCG**. This hormone is structurally similar to LH (Luteinizing Hormone) and binds to LH receptors on the corpus luteum. This "rescues" or salvages the CL, preventing its regression and stimulating it to continue producing **progesterone**, which is vital for maintaining the decidua and the early pregnancy until the placenta takes over (luteal-placental shift) at around 7–10 weeks. **2. Why the other options are incorrect:** * **FSH (Follicle Stimulating Hormone):** Its primary role is the recruitment and growth of ovarian follicles during the follicular phase; it does not maintain the corpus luteum. * **AFP (Alpha-Fetoprotein):** This is a glycoprotein produced by the fetal yolk sac and liver. It serves as a marker for neural tube defects and chromosomal anomalies but has no endocrine role in maintaining the CL. * **Estrogen:** While produced by the CL and the placenta, estrogen does not "salvage" the CL; rather, its rising levels are a result of a functional CL or placenta. **Clinical Pearls for NEET-PG:** * **Doubling Time:** In early pregnancy, hCG levels double every 48 hours. * **Luteal-Placental Shift:** Occurs between **7–10 weeks**. If the corpus luteum is removed before 7 weeks without progesterone supplementation, miscarriage will occur. * **Structure:** hCG is a glycoprotein with an $\alpha$ and $\beta$ subunit. The **$\beta$ subunit** is unique and used for pregnancy testing.

Question 43: What is the drug of choice for imminent eclampsia?

A. Hydralazine
B. Labetalol
C. Magnesium sulfate (Correct Answer)
D. Methyldopa

Explanation: **Explanation:** **Magnesium Sulfate (MgSO₄)** is the drug of choice for both the **prevention** of seizures in imminent eclampsia and the **treatment** of seizures in established eclampsia. The underlying medical concept relies on its role as a potent neuromuscular blocker and CNS depressant. It acts by inhibiting NMDA receptors, blocking calcium influx into neurons, and decreasing acetylcholine release at the motor endplate, thereby raising the seizure threshold. Large-scale trials (like the Magpie Trial) have proven its superiority over diazepam and phenytoin in preventing the progression of pre-eclampsia to eclampsia. **Analysis of Incorrect Options:** * **Hydralazine (A) & Labetalol (B):** These are antihypertensive agents. While they are used to manage hypertensive emergencies in pregnancy (BP ≥160/110 mmHg), they do not possess anti-convulsant properties and cannot prevent seizures. Labetalol is often the first-line IV antihypertensive, but it is not the drug of choice for "imminent eclampsia." * **Methyldopa (D):** This is a centrally acting alpha-2 agonist. It is the drug of choice for **chronic hypertension** in pregnancy due to its long-term safety profile, but it is too slow-acting for acute management or seizure prophylaxis. **High-Yield Clinical Pearls for NEET-PG:** * **Pritchard Regimen:** 4g IV (loading) + 10g IM (5g in each buttock), followed by 5g IM every 4 hours. * **Therapeutic Range:** 4–7 mEq/L. * **Monitoring:** Always check for **Patellar reflex** (earliest sign of toxicity), **Respiratory rate** (>12/min), and **Urine output** (>30ml/hr). * **Antidote:** 10 ml of 10% **Calcium Gluconate** IV (given over 10 minutes).

Question 44: What is the main source of prolactin in amniotic fluid?

A. Decidua (Correct Answer)
B. Syncytiotrophoblast
C. Cytotrophoblast
D. Yolk sac of fetus

Explanation: **Explanation:** The correct answer is **Decidua**. **1. Why Decidua is the correct answer:** While prolactin is primarily secreted by the anterior pituitary gland in non-pregnant states, during pregnancy, the **decidua** (the modified endometrium) becomes a major extra-pituitary source. Decidual cells synthesize and secrete prolactin into the amniotic fluid via a process regulated by local factors (like IGF-1 and cytokines) rather than dopamine. Prolactin levels in amniotic fluid are significantly higher (up to 10–100 times) than in maternal or fetal plasma, peaking at 15–20 weeks of gestation. Its primary role in the amniotic fluid is **osmoregulation**, preventing fetal dehydration by regulating the transport of water and electrolytes across the chorioamnion. **2. Why the other options are incorrect:** * **Syncytiotrophoblast:** This layer is the primary source of **hCG** (human Chorionic Gonadotropin) and **hPL** (human Placental Lactogen), not prolactin. * **Cytotrophoblast:** These are the stem cells of the placenta that primarily secrete **GnRH** and other releasing hormones. * **Yolk sac of fetus:** The yolk sac is responsible for early hematopoiesis and the production of **Alpha-fetoprotein (AFP)**, but it does not contribute to amniotic prolactin levels. **Clinical Pearls for NEET-PG:** * **Source of Amniotic Prolactin:** Decidua (specifically the decidua capsularis and parietalis). * **Source of Maternal Serum Prolactin:** Maternal Anterior Pituitary. * **Source of Fetal Serum Prolactin:** Fetal Anterior Pituitary. * **Function:** Amniotic prolactin is crucial for maintaining **amniotic fluid volume** and electrolyte balance. * **Bromocriptine Fact:** Dopamine agonists like Bromocriptine inhibit pituitary prolactin but **do not** inhibit decidual prolactin production.

Question 45: All of the following are true about gestational diabetes except:

A. Increased chances of recurrence in subsequent pregnancies.
B. Approximately one-third of cases progress to permanent diabetes. (Correct Answer)
C. Congenital malformations are common complications.
D. Insulin is the treatment of choice.

Explanation: **Explanation:** **Why Option B is the Correct Answer (The False Statement):** The statement that "one-third of cases progress to permanent diabetes" is incorrect because the actual risk is significantly higher. Approximately **50% to 70%** of women with Gestational Diabetes Mellitus (GDM) develop Type 2 Diabetes Mellitus within 15–20 years after delivery. While about 10% are diagnosed with diabetes immediately postpartum, the long-term progression rate far exceeds one-third. **Analysis of Other Options:** * **Option A:** GDM has a high recurrence rate, ranging from **30% to 70%** in subsequent pregnancies, making this a true statement. * **Option C:** This is a **true statement** in the context of clinical exams. While congenital malformations are primarily associated with *pre-gestational* diabetes (due to hyperglycemia during organogenesis), GDM is often diagnosed late. However, many women have undiagnosed Type 2 DM (overt diabetes) discovered during pregnancy screening; these cases carry a high risk of malformations like **Sacral Agenesis** (most specific) and Cardiac defects. * **Option D:** **Insulin** remains the gold standard and treatment of choice for GDM when medical nutrition therapy (MNT) fails, as it does not cross the placenta and allows for precise glycemic control. **High-Yield Clinical Pearls for NEET-PG:** * **Screening:** Done at 24–28 weeks using the **DIPSI criteria** (75g glucose, 2-hour value ≥140 mg/dL). * **Most Common Malformation:** Ventricular Septal Defect (VSD). * **Most Specific Malformation:** Sacral Agenesis (Caudal Regression Syndrome). * **Target Glycemia:** Fasting <95 mg/dL, 1-hr postprandial <140 mg/dL, or 2-hr postprandial <120 mg/dL. * **Postpartum Follow-up:** A 75g OGTT should be performed **6–12 weeks after delivery** to screen for persistent diabetes.

Question 46: Which of the following is NOT correct regarding respiratory function during the late trimester of normal pregnancy?

A. Tidal volume and resting minute ventilation increase.
B. Functional residual capacity and residual volume are decreased.
C. Lung compliance is decreased. (Correct Answer)
D. Total pulmonary resistance is reduced.

Explanation: In normal pregnancy, significant physiological adaptations occur in the respiratory system to meet the increased oxygen demands of the fetus and the mother. **Explanation of the Correct Answer (C):** **Lung compliance does NOT change** during pregnancy. While the enlarging uterus causes the diaphragm to rise by approximately 4 cm, the chest wall diameter increases and the ribs flare out (mediated by the hormone relaxin). This maintains the overall compliance of the respiratory system. Therefore, the statement that lung compliance is decreased is incorrect. **Analysis of Incorrect Options:** * **Option A:** Progesterone acts as a direct respiratory stimulant. It increases the sensitivity of the respiratory center to $CO_2$, leading to an increase in **Tidal Volume (by ~40%)** and **Resting Minute Ventilation (by ~40-50%)**. * **Option B:** Due to the elevation of the diaphragm, the **Functional Residual Capacity (FRC)** and **Residual Volume (RV)** are decreased by approximately 20%. This is a high-yield fact often tested in exams. * **Option D:** Progesterone causes relaxation of the smooth muscles in the tracheobronchial tree, which leads to a **reduction in total pulmonary resistance**. **High-Yield NEET-PG Pearls:** 1. **Vital Capacity (VC)** and **Inspiratory Capacity (IC)** remain unchanged or may slightly increase. 2. **Respiratory Rate** remains largely **unchanged**; the increase in minute ventilation is primarily due to increased tidal volume. 3. Pregnancy is a state of **compensated respiratory alkalosis** (pH 7.40–7.45) due to hyperventilation, which facilitates $CO_2$ transfer from the fetus to the mother. 4. **Dyspnea of pregnancy** is common and physiological, often starting in the first or second trimester.

Question 47: When is termination of pregnancy indicated in hyperemesis gravidarum?

A. Presence of acetone in urine
B. Decrease in renal output (Correct Answer)
C. Vomiting persists beyond three months
D. All of the above

Explanation: **Explanation:** Hyperemesis Gravidarum (HG) is a severe form of nausea and vomiting in pregnancy that leads to dehydration, electrolyte imbalance, and weight loss. While modern supportive care makes termination of pregnancy (TOP) rare, it remains a life-saving indication when conservative management fails and multi-organ dysfunction begins. **Why "Decrease in renal output" is the correct answer:** A decrease in renal output (oliguria) signifies severe, decompensated dehydration and the onset of **acute kidney injury (AKI)**. In the context of HG, this indicates that the body’s compensatory mechanisms have failed. Along with other "danger signs" like jaundice (liver failure), retinal hemorrhage, or Wernicke’s encephalopathy (neurological damage), persistent oliguria is a definitive indication for termination to save the mother’s life. **Why the other options are incorrect:** * **A. Presence of acetone in urine:** Ketonuria is a common finding in HG due to starvation and fat metabolism. It is a marker for hospitalization and IV fluid resuscitation, not an indication for termination. * **C. Vomiting persists beyond three months:** While HG typically resolves by 16–20 weeks, persistence alone is not life-threatening. Many women continue to have mild symptoms throughout pregnancy without requiring termination. **NEET-PG High-Yield Pearls:** * **Wernicke’s Encephalopathy:** Caused by Vitamin B1 (Thiamine) deficiency due to prolonged vomiting. Always replenish Thiamine *before* giving Glucose to avoid precipitating this condition. * **Electrolyte Imbalance:** The most common pattern is **Hypokalemic Hypochloremic Metabolic Alkalosis**. * **Mallory-Weiss Tear:** Hematemesis in HG is often due to esophageal mucosal tears from forceful vomiting. * **Drug of Choice:** Pyridoxine (Vitamin B6) + Doxylamine is the first-line pharmacological treatment.

Question 48: Which of the following is true of thyroid nodules during pregnancy?

A. Are poorly assessed by fine-needle aspiration.
B. Can be safely removed before 24 weeks gestation. (Correct Answer)
C. When smaller than 0.5 cm, can be reliably detected sonographically.
D. If cancerous, confer worse prognosis than if found in non-pregnant controls.

Explanation: ### Explanation Thyroid nodules are common during pregnancy due to the stimulatory effect of hCG and relative iodine deficiency. Management follows protocols similar to non-pregnant patients, with specific timing considerations for surgery. **Why Option B is Correct:** If a thyroid nodule is suspicious for malignancy (based on FNA) or is causing compressive symptoms, surgical intervention is indicated. The **second trimester (before 24 weeks)** is the safest window for surgery. During this period, organogenesis is complete (reducing teratogenic risk), and the uterus is not yet large enough to impede surgical access or cause significant vena cava compression, minimizing the risk of preterm labor compared to the third trimester. **Analysis of Incorrect Options:** * **Option A:** Fine-needle aspiration (FNA) remains the **gold standard** for assessing thyroid nodules in pregnancy. It is safe, reliable, and has the same diagnostic accuracy as in non-pregnant individuals. * **Option C:** While ultrasonography is the preferred imaging modality, nodules **smaller than 1 cm** are difficult to characterize reliably and often do not require FNA unless high-risk features are present. 0.5 cm is below the standard clinical threshold for reliable detection and biopsy. * **Option D:** Pregnancy **does not worsen the prognosis** of thyroid cancer. Differentiated thyroid carcinomas (like papillary) diagnosed during pregnancy have similar recurrence and survival rates as those diagnosed in non-pregnant women. **High-Yield Clinical Pearls for NEET-PG:** * **First-line investigation:** Serum TSH and Ultrasound. * **Radioactive Iodine (I-131) Scan:** Absolutely **contraindicated** in pregnancy as it crosses the placenta and can destroy the fetal thyroid gland. * **Suppressive Therapy:** If surgery is deferred until postpartum, L-thyroxine is given to keep TSH in the low-normal range (0.1–1.5 mU/L) to prevent TSH-induced tumor growth.

Question 49: Related to calcium metabolism, which of the following does not occur during pregnancy?

A. Total serum calcium levels fall.
B. 80% of fetal calcium deposition occurs in the third trimester.
C. Fetal skeleton excretes approximately 30g of calcium by term.
D. Serum ionized calcium levels fall. (Correct Answer)

Explanation: ### Explanation The physiological changes in calcium metabolism during pregnancy are designed to ensure an adequate supply of calcium to the developing fetus while maintaining maternal homeostasis. **1. Why Option D is the correct answer (Why it does NOT occur):** In pregnancy, **serum ionized calcium levels remain constant.** While total serum calcium decreases, the physiologically active form (ionized calcium) is strictly regulated by parathyroid hormone (PTH) and 1,25-dihydroxyvitamin D. Maintaining stable ionized calcium levels is crucial for maternal neuromuscular function and fetal skeletal development. **2. Analysis of Incorrect Options:** * **Option A (Total serum calcium levels fall):** This **does occur**. During pregnancy, there is a significant increase in plasma volume leading to hemodilution. This results in a decrease in serum albumin levels. Since about 50% of calcium is bound to albumin, the **total** serum calcium concentration falls, even though the ionized fraction remains stable. * **Option B (80% of fetal calcium deposition occurs in the third trimester):** This **is true**. Fetal calcium demands peak in the third trimester to support rapid skeletal mineralization. Approximately 250–300 mg of calcium is transferred to the fetus daily during this period. * **Option C (Fetal skeleton accretes approx. 30g of calcium by term):** This **is true**. By the end of pregnancy, the fetus has accumulated roughly 28–30 grams of calcium, the vast majority of which is stored in the fetal skeleton. ### NEET-PG High-Yield Pearls: * **Primary Adaptation:** Maternal calcium absorption in the gut **doubles** as early as the 12th week of gestation, mediated by an increase in 1,25-dihydroxyvitamin D. * **PTH levels:** PTH levels typically decrease in the first trimester but may rise slightly back to the normal range by term. * **Calcitonin:** Levels increase during pregnancy to protect the maternal skeleton from excessive resorption. * **Fetal State:** The fetus is relatively **hypercalcemic** compared to the mother, maintained by active placental transport.

Question 50: What is true about diabetes in pregnancy?

A. Macrosomia
B. Intrauterine growth restriction (IUGR)
C. Congenital anomalies
D. All of the above (Correct Answer)

Explanation: Diabetes in pregnancy encompasses both **Pre-gestational (Type 1 or 2)** and **Gestational Diabetes Mellitus (GDM)**. The fetal outcomes depend significantly on the timing and severity of hyperglycemia. ### **Explanation of Options:** * **A. Macrosomia:** This is the most common complication. According to the **Pedersen Hypothesis**, maternal hyperglycemia leads to fetal hyperglycemia. This stimulates the fetal pancreas to secrete excess insulin (hyperinsulinemia). Since insulin is a potent growth hormone, it causes excessive deposition of fat and glycogen, leading to a large-for-gestational-age fetus (>4kg). * **B. Intrauterine Growth Restriction (IUGR):** While GDM typically causes macrosomia, **Pre-gestational diabetes** (especially with long-standing vascular complications like White’s Class R or F) can lead to placental insufficiency. This results in restricted nutrient delivery, causing IUGR. * **C. Congenital Anomalies:** These occur due to **teratogenicity** from hyperglycemia during organogenesis (first trimester). Therefore, they are seen in **Pre-gestational diabetes** but *not* in GDM (which develops after the first trimester). The most specific anomaly is **Caudal Regression Syndrome**, though Cardiac defects (VSD) are the most common. ### **High-Yield Clinical Pearls for NEET-PG:** * **Most common malformation:** Ventricular Septal Defect (VSD). * **Most specific malformation:** Caudal Regression Syndrome (Sacral agenesis). * **HbA1c Goal:** Ideally <6.0% pre-conception to minimize anomaly risks. * **Neonatal Complications:** Hypoglycemia (due to persistent fetal hyperinsulinemia), Hypocalcemia, Hyperbilirubinemia, and Polycythemia. * **Respiratory Distress Syndrome (RDS):** Hyperinsulinemia inhibits cortisol-induced surfactant production by Type II pneumocytes.

Practice by Chapter

Endocrine Changes in Normal Pregnancy

Practice Questions

Thyroid Disorders in Pregnancy

Practice Questions

Diabetes in Pregnancy

Practice Questions

Adrenal Disorders in Pregnancy

Practice Questions

Pituitary Disorders in Pregnancy

Practice Questions

Hyperemesis Gravidarum

Practice Questions

Hormonal Regulation of Labor

Practice Questions

Pharmacokinetics of Hormones in Pregnancy

Practice Questions

Fetal Endocrine Development

Practice Questions

Placental Hormones

Practice Questions

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