Maternal-Fetal Medicine and Antenatal Assessment
Antenatal assessment sets the delivery-room trajectory
Candidates must connect maternal conditions to fetal risk: hypertensive disorders, diabetes, isoimmunization, infection, multiple gestation, and preterm labor. Know the evidence-based windows: antenatal corticosteroids for threatened preterm birth at 24–34 weeks, magnesium sulfate for neuroprotection when delivery is expected before 32 weeks, and group B streptococcus prophylaxis for preterm labor, prolonged rupture, or maternal fever. Fetal surveillance includes category I/II/III heart-rate interpretation, biophysical profile, umbilical artery Doppler in growth restriction, and amniotic-fluid assessment. Timing of delivery balances stillbirth risk against prematurity; for example, uncomplicated dichorionic twins are often delivered around 37 weeks, while severe preeclampsia before 34 weeks may warrant delivery after steroids.
Traps: confusing betamethasone and dexamethasone regimens; assuming any late-preterm delivery needs magnesium; treating category II tracings as uniformly normal; and missing that GBS prophylaxis requires adequate duration (penicillin at least four hours before delivery) rather than merely starting the drug. Also distinguish late decelerations (uteroplacental insufficiency) from variable decelerations (cord compression) and from a sinusoidal pattern (fetal anemia).
Worked example: a 29-week gestation with preterm labor and ruptured membranes receives betamethasone, magnesium sulfate, and intravenous penicillin. The team plans delivery with a neonatal resuscitation team present, anticipating respiratory distress syndrome and possible early-onset sepsis.
Rule of thumb: “Steroids before 34, magnesium before 32, and GBS coverage when membranes are ruptured or labor is preterm.”