Pregnancy, Antepartum, and Postpartum Care
What the exam tests
Obstetric items cluster around dating, routine prenatal care, hypertensive disorders, and postpartum complications. Know thresholds and timelines precisely.
Core concepts
- Dating: first-trimester ultrasound (crown-rump length) is most accurate; last menstrual period alone can misdate.
- Routine prenatal labs: CBC, blood type, Rh, and antibody screen, rubella and varicella immunity, syphilis, HIV, hepatitis B, chlamydia and gonorrhea, urine culture; aneuploidy screening offered.
- Gestational diabetes: screen at 24-28 weeks, earlier with risk factors.
- Group B streptococcus: culture at 36 0/7 to 37 6/7 weeks.
- Rh prophylaxis at 28 weeks and within 72 hours postpartum if Rh-negative and unsensitized.
- Preeclampsia: new hypertension at 20 weeks or later plus proteinuria or severe features (thrombocytopenia, renal or liver dysfunction, pulmonary edema, visual or cerebral symptoms). Magnesium sulfate prevents and treats seizures but is not an antihypertensive; labetalol, nifedipine, and hydralazine treat severe-range pressures.
- Postpartum: uterine atony is the most common cause of hemorrhage, managed with fundal massage and uterotonics. Screen for depression at postpartum visits.
Traps
- Giving live vaccines (MMR, varicella) during pregnancy.
- Using methotrexate or ACE inhibitors in pregnancy.
- Treating blood pressure but forgetting seizure prophylaxis in severe preeclampsia.
- Clinging to an LMP-based due date when an early ultrasound disagrees.
Worked example
A patient at 34 weeks has BP 164/110, persistent headache, and 3+ proteinuria. This is preeclampsia with severe features: admit, start magnesium sulfate for seizure prophylaxis, treat pressures with labetalol or nifedipine, and plan delivery at 34 weeks or later.