The B-hCG curve in maternal serum in a normal pregnancy peaks at: A. 6 weeks of pregnancy. B. 8 weeks of pregnancy. C. 10 weeks of pregnancy. D. 14 weeks of pregnancy. E. 18 weeks of pregnancy.
Reading File
Finding Sources
The answer is C. 10 weeks of pregnancy.
β-hCG in Normal Pregnancy
β-hCG (beta human chorionic gonadotropin) is produced by syncytiotrophoblast cells of the developing placenta. Its serum concentration follows a characteristic pattern:
- Rises rapidly after implantation (~6–8 days post-fertilization), doubling approximately every 48–72 hours in early pregnancy.
- Peaks at approximately 10 weeks of gestation (range reported across sources: 8–12 weeks), reaching levels of roughly 50,000–100,000+ mIU/mL.
- Declines after the peak, falling by ~90% by the end of the second trimester, then plateaus for the remainder of pregnancy.
What the textbooks say:
| Source | Peak stated |
|---|---|
| Berek & Novak's Gynecology | ~10 weeks |
| Rosen's Emergency Medicine | 7–10 weeks, mean 50,000 IU/L |
| Henry's Clinical Diagnosis (Lab Methods) | ~10–12 weeks |
| Roberts & Hedges' Clinical Procedures | 10th–14th gestational weeks |
| Creasy & Resnik's Maternal-Fetal Medicine | 8–12 weeks, then declines |
The most consistently cited peak is 10 weeks (end of first trimester), which is why option C is the standard correct answer in obstetrics examinations.
Berek & Novak's Gynecology: "β-hCG levels peak at approximately 10 weeks…" Rosen's Emergency Medicine: "β-hCG levels should peak at the 7- to 10-week range."
QUE no 25: A 38-year-old G2P1 presents at 28 weeks of gestation with the history of headache and increase Blood Pressure of 160/100mmHg for 7 days but no history of body swelling. There is n detected in her urine. Which of following drug is MOST appropriate for this ACE inhibitors Beta blockers Methyl dopa diuretics
Finding Sources
Finding Sources
The answer is C. Methyldopa.
Clinical Analysis
Diagnosis: This patient has gestational hypertension (non-proteinuric hypertension after 20 weeks gestation):
- 28 weeks gestation
- BP 160/100 mmHg for 7 days
- Headache
- No proteinuria (no protein detected in urine)
- No edema
This rules out pre-eclampsia (which requires proteinuria ≥ 300 mg/24h or other end-organ features). The BP of 160/100 qualifies as severe-range hypertension requiring treatment.
Why Methyldopa?
Methyldopa is the first-line oral antihypertensive in pregnancy, supported across multiple major textbooks:
| Drug | Status in Pregnancy |
|---|---|
| Methyldopa | ✅ First-line — longest safety record, no fetal harm demonstrated |
| Beta-blockers (labetalol) | ✅ Used, but atenolol avoided; non-selective β-blockers may cause fetal bradycardia/IUGR |
| ACE inhibitors | ❌ Contraindicated — fetal renal dysplasia, oligohydramnios, pulmonary hypoplasia, fetal death |
| Diuretics | ❌ Not first-line — reduce already-decreased plasma volume in pregnancy; may worsen uteroplacental perfusion |
Brenner & Rector's The Kidney: "Methyldopa continues to be the first-line oral agent for the management [of hypertension in pregnancy]."
Creasy & Resnik's Maternal-Fetal Medicine: "Labetalol, nifedipine, and methyldopa are the recommended first-line agents for treatment of hypertension in pregnancy."
Harrison's Principles of Internal Medicine 22E: "ACE inhibitors and angiotensin-receptor blockers are contraindicated in pregnancy."
Why the Others Are Wrong
- ACE inhibitors — Absolutely contraindicated in the 2nd and 3rd trimesters. Cause fetal renal tubular dysplasia, oligohydramnios, skull hypoplasia, and neonatal renal failure.
- Beta-blockers (non-specific) — Can be used (labetalol is acceptable), but as a class they are not preferred over methyldopa in standard exam contexts; atenolol specifically causes IUGR.
- Diuretics — Contraindicated as first-line in pregnancy; they reduce circulating volume which is already physiologically altered in pregnancy, potentially harming fetal perfusion.
Answer: C. Methyldopa
QUE no 20: A 40-years-old G2P1 at 17 weeks of gestation came for an antenatal checkup. She previously had Down syndrome baby and is concerned for this pregnancy. What is the ideal investigation for screening of Down syndrome in this patient? A. Combined screening test B. Quadruple test C.Serum BHCG D.Ultrasound for nuchal translucency
Finding Sources
Finding Sources
The answer is B. Quadruple test.
Key Clinical Reasoning
The critical factor here is gestational age: 17 weeks.
| Screening Test | Optimal Gestational Age | Components |
|---|---|---|
| Combined screening test | 11–13+6 weeks (1st trimester) | NT ultrasound + PAPP-A + β-hCG |
| Nuchal translucency (NT) alone | 11–13+6 weeks | Ultrasound only |
| Quadruple test | 15–20 weeks (2nd trimester) | AFP + uE3 + hCG + Inhibin A |
| Serum β-hCG alone | Not used as sole screening | Poor sensitivity alone |
At 17 weeks, the patient is firmly in the second trimester:
- The combined test window has already closed (it requires NT measurement, which is only reliable between 11–14 weeks).
- NT ultrasound alone is also no longer valid at 17 weeks.
- Serum β-hCG alone has insufficient sensitivity as a standalone screen.
The Quadruple test (also called the "Quad screen") is the standard second-trimester screening test for Down syndrome, measuring:
- AFP (alpha-fetoprotein) — ↓ in Down syndrome
- uE3 (unconjugated estriol) — ↓ in Down syndrome
- hCG — ↑ in Down syndrome
- Inhibin A — ↑ in Down syndrome
Swanson's Family Medicine Review: "The quadruple test is currently used most widely in the United States for screening in the second trimester for Down syndrome. At a second-trimester cutoff of 1 in 250, the detection rate is 80%, with a 5% false-positive rate."
Emery's Elements of Medical Genetics and Genomics: "Low levels of uE3 and elevated levels of inhibin-A are associated with Down syndrome in the second trimester."
Additional Notes
- Her age (40 years) and prior Down syndrome baby both increase her risk, reinforcing the need for screening.
- If screening is positive, amniocentesis (karyotyping) would be the definitive diagnostic step at this gestational age.
- The integrated test (NT in 1st trimester + quad markers in 2nd) gives the highest detection rate (~85%), but since her first-trimester window has passed, the quad test alone is now the most appropriate choice.
Answer: B. Quadruple test
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