Maternal-Fetal Medicine and High-Risk Pregnancy
What the exam tests
This domain tests risk stratification, hypertensive disorders, diabetes, fetal growth restriction, preterm birth, and multiple pregnancy. Expect questions on timing of delivery, steroid use, and fetal surveillance.
Core rules
- First-trimester combined screening at 11–13+6 weeks uses nuchal translucency, free β-hCG, and PAPP-A; cell-free DNA is a screening test, not diagnostic.
- Preeclampsia is new hypertension after 20 weeks plus proteinuria or maternal organ dysfunction. Severe features include BP ≥160/110, platelets <100 × 10⁹/L, elevated transaminases, renal insufficiency, pulmonary oedema, or neurological symptoms.
- High-risk women start aspirin 75–150 mg at 12–16 weeks for preeclampsia prevention.
- Magnesium sulfate is for seizure prophylaxis in severe preeclampsia; delivery is the definitive treatment. Without severe features, deliver at 37 weeks; with severe features, at 34 weeks unless unstable.
- Betamethasone 12 mg IM twice, 24 hours apart, for threatened preterm birth at 24–34 weeks.
Worked example
A 32-week primigravida has BP 165/110, 3+ proteinuria, platelets 90 × 10⁹/L, headache, and AST twice normal. This is preeclampsia with severe features. Admit, start magnesium sulfate, control BP with labetalol or nifedipine, give betamethasone, and plan delivery after stabilisation. The reasoning: severe features at <34 weeks justify steroids but not expectant management beyond maternal safety.
Traps
Diagnosing preeclampsia before 20 weeks; requiring proteinuria when organ dysfunction is present; continuing magnesium without checking reflexes and urine output; and missing HELLP syndrome.