Endocrinology of Pregnancy Practice Questions

Q: What are the threshold values for the diagnosis of Gestational Diabetes Mellitus using a 75g Oral Glucose Tolerance Test?

Fasting: 92 mg/dL, 1-hour: 180 mg/dL, 2-hour: 153 mg/dL. The diagnosis of Gestational Diabetes Mellitus (GDM) has been standardized globally by the **IADPSG (International Association of Diabetes and Pregnancy Study Groups)** and adopted by the **WHO**. ### 1. Why Option A is Correct The IADPSG criteria utilize a **one-step 75g Oral Glucose Tolerance Test (OGTT)** performed between 24–28 weeks of gestation. GDM is diagnosed if **one or more** of the following plasma glucose values are met or exceeded: * **Fasting:** 92 mg/dL * **1-hour:** 180 mg/dL * **2-hour:** 153 mg/dL These thresholds were derived from the HAPO study, which identified these specific levels as the points where the risk for adverse neonatal outcomes (like macrosomia) significantly increases. ### 2. Analysis of Incorrect Options * **Option B & D (155 mg/dL):** The 155 mg/dL value for the 2-hour mark is part of the older **Carpenter-Coustan criteria** (which uses a 100g, 3-hour OGTT). It is not used in the modern 75g IADPSG/WHO protocol. * **Option C & D (95 mg/dL):** The fasting value of 95 mg/dL is also associated with the Carpenter-Coustan or NDDG criteria. The IADPSG criteria use a stricter fasting cutoff of **92 mg/dL**. ### 3. NEET-PG High-Yield Pearls * **DIPSI Guidelines (India):** In the Indian context, the DIPSI (Diabetes in Pregnancy Study Group India) recommends a "single-step" 75g test regardless of the last meal. A **2-hour value ≥ 140 mg/dL** is diagnostic. * **Screening Time:** Routine screening is done at **24–28 weeks**. High-risk patients should be screened at the first prenatal visit. * **Overt Diabetes:** If Fasting is ≥ 126 mg/dL or HbA1c is ≥ 6.5% at the first visit, it is classified as "Overt/Pre-gestational Diabetes," not GDM.

Q: What are the changes in the respiratory system during pregnancy?

Residual volume is decreased. **Explanation:** Respiratory changes in pregnancy are primarily driven by the mechanical effects of the enlarging uterus and the stimulatory effects of progesterone. **Why the correct answer (D) is right:** As the uterus enlarges, it elevates the diaphragm by approximately 4 cm. This upward displacement reduces the space available in the lungs at the end of expiration. Consequently, the **Residual Volume (RV)** and the **Functional Residual Capacity (FC)** decrease by approximately 20%. Despite the elevation, diaphragmatic excursion actually increases to maintain ventilation. **Analysis of incorrect options:** * **A. Vital capacity is increased:** Vital capacity (VC) remains **unchanged** or may show a very slight increase. While the diaphragm rises, there is a compensatory increase in the transverse and anteroposterior diameters of the chest wall. * **B. Subcostal angle remains unchanged:** The subcostal angle **increases** significantly (from about 68° to 103°) due to the hormonal relaxation of rib ligaments and the mechanical pressure of the uterus, widening the thoracic cage. * **C. Tidal volume remains unaltered:** Tidal volume (TV) **increases** by approximately 40%. Progesterone acts as a direct respiratory stimulant, increasing the sensitivity of the respiratory center to CO2, leading to deeper breaths (hyperventilation of pregnancy). **High-Yield NEET-PG Pearls:** * **Most common change:** Increase in Tidal Volume. * **Parameters that Decrease:** Residual Volume (RV), Functional Residual Capacity (FRC), Total Lung Capacity (TLC), and Expiratory Reserve Volume (ERV). * **Parameters that Increase:** Tidal Volume (TV), Minute Ventilation, and Inspiratory Capacity. * **Acid-Base Status:** Pregnancy is a state of **compensated respiratory alkalosis** (decreased $PCO_2$ to facilitate CO2 transfer from the fetus).

Q: The corpus luteum supports the endometrium in pregnancy until which gestational period?

6-10 weeks. **Explanation:** The maintenance of early pregnancy depends on the secretion of progesterone by the **corpus luteum of pregnancy**. This process is driven by Human Chorionic Gonadotropin (hCG), which rescues the corpus luteum from regression. 1. **Why Option A is Correct:** The transition of progesterone production from the corpus luteum to the placenta is known as the **Luteal-Placental Shift**. This shift begins around the 6th-7th week and is typically complete by the **10th week** of gestation. While the corpus luteum persists throughout pregnancy, its functional necessity for endometrial support ends once the trophoblastic cells (placenta) produce sufficient progesterone to maintain the pregnancy independently. 2. **Why Other Options are Incorrect:** * **Option B (12-24 weeks):** By 12 weeks, the placenta is the primary source of progesterone. Surgical removal of the corpus luteum after 10 weeks usually does not result in miscarriage. * **Options C & D (36-42 weeks):** These represent late third trimester and post-term periods. The corpus luteum is functionally redundant for hormonal support long before this stage. **NEET-PG High-Yield Pearls:** * **Luteectomy:** If the corpus luteum is surgically removed before **8 weeks**, exogenous progesterone supplementation is mandatory to prevent abortion. Between 8–10 weeks, it is controversial but often supplemented. After 10 weeks, it is generally unnecessary. * **hCG Peak:** hCG levels peak at approximately **8–10 weeks**, coinciding with the maximum stimulation of the corpus luteum before the placental shift is finalized. * **Source of Progesterone:** 0–6 weeks (Corpus Luteum); 7–10 weeks (Transition); >10 weeks (Placenta).

Q: In Gestational diabetes mellitus, what is NOT usually seen?

Malformations like cardiac and neural tube defects. The key to answering this question lies in distinguishing between **Gestational Diabetes Mellitus (GDM)** and **Pregestational (Overt) Diabetes**. ### Why Option B is the Correct Answer Congenital malformations (such as cardiac defects, neural tube defects, and sacral agenesis) occur during **organogenesis**, which takes place in the **first 8 weeks** of gestation. * In **GDM**, hyperglycemia typically develops in the late second or third trimester (after 24 weeks) due to increased insulin resistance from placental hormones (hPL). Since blood glucose is normal during the first trimester, the risk of structural malformations is **not increased** compared to the general population. * In contrast, **Pregestational Diabetes** involves hyperglycemia during conception and early pregnancy, which is highly teratogenic. ### Why the Other Options are Incorrect * **A. Macrosomic baby:** Maternal hyperglycemia leads to fetal hyperglycemia. The fetal pancreas responds by secreting excess insulin (a potent growth hormone), leading to fetal overgrowth (macrosomia). * **C. Shoulder dystocia:** Macrosomia in GDM involves disproportionate fat deposition around the shoulders and abdomen, significantly increasing the risk of the shoulders getting stuck during delivery. * **D. Polyhydramnios:** Fetal hyperglycemia causes osmotic diuresis, leading to fetal polyuria, which increases the volume of amniotic fluid. ### NEET-PG High-Yield Pearls * **Most common malformation in Overt Diabetes:** Ventricular Septal Defect (VSD). * **Most specific malformation in Overt Diabetes:** Caudal Regression Syndrome (Sacral Agenesis). * **Screening for GDM:** Best done at 24–28 weeks using the DIPSI criteria (75g oral glucose; positive if 2-hour value $\geq$ 140 mg/dL). * **Target Blood Sugars in GDM:** Fasting $<95$ mg/dL; 1-hour postprandial $<140$ mg/dL; 2-hour postprandial $<120$ mg/dL.

Q: A 32-year-old female with diabetes presents at 6 weeks of amenorrhea. She is not on any treatment. What is the first step in her management?

Perform HbA1c test. **Explanation:** The correct answer is **C. Perform HbA1c test.** **1. Why HbA1c is the first step:** In a patient with pre-existing diabetes (or suspected overt diabetes) presenting in the first trimester, the primary concern is the risk of **congenital malformations**. HbA1c reflects glycemic control over the preceding 8–12 weeks, covering the critical period of organogenesis. A high HbA1c level (>7%) is strongly associated with an increased risk of anomalies (e.g., Sacral agenesis, VSD). It serves as a baseline to assess the risk of teratogenicity and guides the intensity of management. **2. Why other options are incorrect:** * **A & B (Insulin/Diet):** While glycemic control is essential, management cannot be initiated without first assessing the severity of the baseline glycemic status and the risk to the fetus. HbA1c provides the necessary prognostic information before deciding on the therapeutic regimen. * **D (Postprandial glucose):** While daily monitoring is vital for ongoing management, a single point-in-time glucose test does not provide information about the glycemic control during the early weeks of pregnancy (organogenesis), which is the priority at 6 weeks gestation. **3. NEET-PG High-Yield Pearls:** * **Most common malformation** in infants of diabetic mothers: **VSD** (Ventricular Septal Defect). * **Most specific malformation:** **Caudal Regression Syndrome** (Sacral Agenesis). * **Target HbA1c:** Ideally, HbA1c should be **<6.5%** (or <6% if achievable without hypoglycemia) to minimize the risk of malformations. * **Overt Diabetes vs. GDM:** If fasting plasma glucose is ≥126 mg/dL or HbA1c is ≥6.5% at the first prenatal visit, it is classified as **Overt Diabetes**, not Gestational Diabetes Mellitus (GDM).

Q: Which of the following hormones is NOT secreted by the placenta?

Insulin. **Explanation:** The placenta acts as a sophisticated transient endocrine organ, producing a wide array of protein and steroid hormones to maintain pregnancy. **Why Insulin is the Correct Answer:** Insulin is a peptide hormone produced exclusively by the **beta cells of the Islets of Langerhans in the pancreas**. While the placenta produces hormones that significantly influence maternal glucose metabolism (like Human Placental Lactogen/hPL), it does **not** synthesize insulin. Furthermore, maternal insulin does not cross the placental barrier; the fetus relies entirely on its own pancreatic production for glycemic control. **Analysis of Incorrect Options:** * **hCG (Human Chorionic Gonadotropin):** This is the first hormone secreted by the syncytiotrophoblast. It is essential for maintaining the corpus luteum in early pregnancy. * **TRH (Thyrotropin-Releasing Hormone):** The placenta produces various hypothalamic-like releasing hormones, including TRH, GnRH, and CRH. These function locally to regulate placental hormone secretion. * **ACTH (Adrenocorticotropic Hormone):** The placenta synthesizes POMC-derived peptides, including ACTH. Unlike pituitary ACTH, placental ACTH is relatively resistant to feedback suppression by glucocorticoids. **High-Yield Clinical Pearls for NEET-PG:** * **hPL (Human Placental Lactogen):** Also known as Human Chorionic Somatomammotropin (hCS), it is the primary hormone responsible for the **diabetogenic state** of pregnancy (insulin resistance). * **Progesterone:** Often called the "hormone of pregnancy," the placenta takes over its production from the corpus luteum at approximately **7–9 weeks** (Luteo-placental shift). * **Estriol (E3):** The dominant estrogen in pregnancy; its synthesis requires the **fetal adrenal gland** (DHEAS) and **fetal liver** (16-alpha-hydroxylation), making it a marker of feto-placental well-being.

Question 1

A 30-year-old G3P2 patient at 20 weeks gestation presents to an antenatal clinic. Her first child weighed 4.6 kg and was delivered via cesarean section, and her second child weighed 4.8 kg and was also delivered by cesarean section. Based on this history, gestational diabetes is suspected and a glucose challenge test (GCT) is ordered. The patient's blood sugar level after a 50 g oral glucose load is 206 mg/dl, confirming gestational diabetes. Which of the following is NOT a known complication of gestational diabetes?

Accepted Answer

Congenital malformations in fetus

Answer

Susceptibility for infection

Answer

Fetal hyperglycemia

Answer

Neonatal hypoglycemia

Question 2

What are the threshold values for the diagnosis of Gestational Diabetes Mellitus using a 75g Oral Glucose Tolerance Test?

Accepted Answer

Fasting: 92 mg/dL, 1-hour: 180 mg/dL, 2-hour: 153 mg/dL

Answer

Fasting: 92 mg/dL, 1-hour: 180 mg/dL, 2-hour: 155 mg/dL

Answer

Fasting: 95 mg/dL, 1-hour: 180 mg/dL, 2-hour: 153 mg/dL

Answer

Fasting: 95 mg/dL, 1-hour: 180 mg/dL, 2-hour: 155 mg/dL

Question 3

Which of the following statements regarding hormonal changes during pregnancy is FALSE?

Accepted Answer

The level of hCG is higher in the third trimester compared to the first trimester.

Answer

The level of progesterone is higher in the third trimester compared to the first trimester.

Answer

The level of estriol is lower in the first trimester compared to the third trimester.

Answer

The level of human placental lactogen is lower in the first trimester compared to the third trimester.

Question 4

Gestational diabetes mellitus (GDM) is associated with an increased risk of maternal and fetal/neonatal complications. Which of the following statements about congenital anomalies in diabetes mellitus is FALSE?

Accepted Answer

Single umbilical artery is only seen in gestational diabetes

Answer

Results due to free radical injury

Answer

6-10% of cases are associated with major congenital abnormality

Answer

Insulin can be given

Question 5

What are the changes in the respiratory system during pregnancy?

Accepted Answer

Residual volume is decreased

Answer

Vital capacity is increased

Answer

Subcostal angle remains unchanged

Answer

Tidal volume remains unaltered

Question 6

The corpus luteum supports the endometrium in pregnancy until which gestational period?

Accepted Answer

6-10 weeks

Answer

12-24 weeks

Answer

36 weeks

Answer

42 weeks

Question 7

In Gestational diabetes mellitus, what is NOT usually seen?

Accepted Answer

Malformations like cardiac and neural tube defects

Answer

Macrosomic baby

Answer

Shoulder dystocia

Answer

Polyhydramnios

Question 8

A 16-year-old female presents with primary amenorrhea. Examination shows a short, blind vagina and an absent uterus. What is the next investigation of choice?

Accepted Answer

Karyotyping

Answer

Intravenous pyelogram (IVP)

Answer

Gonadotrophin levels

Answer

Serum prolactin

Question 9

A 32-year-old female with diabetes presents at 6 weeks of amenorrhea. She is not on any treatment. What is the first step in her management?

Accepted Answer

Perform HbA1c test

Answer

Start insulin therapy

Answer

Initiate dietary modifications

Answer

Perform postprandial blood glucose tests

Question 10

Which of the following hormones is NOT secreted by the placenta?

Accepted Answer

Insulin

Answer

hCG

Answer

TRH

Answer

ACTH

Endocrinology of Pregnancy — MCQs

Endocrinology of Pregnancy — MCQs

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