Pharmacology · single question
Which drug is contraindicated in the first trimester of pregnancy?
Show answer and explanation
Correct answer: C. Warfarin (Coumadin®)
Warfarin is a teratogen absolutely contraindicated in the first trimester (weeks 6-12). It crosses the placenta and causes 'fetal warfarin syndrome' (nasal hypoplasia, stippled epiphyses, growth retardation, CNS anomalies). Heparin does NOT cross the placenta and is the anticoagulant of choice during pregnancy. Acetaminophen and diphenhydramine are Category B and generally considered safe in pregnancy.
- A. INCORRECT. Diphenhydramine (Benadryl) is FDA Category B and is commonly used for allergies and as a sleep aid during pregnancy — it is not contraindicated.
- B. INCORRECT. Acetaminophen is FDA Category B and is the analgesic of choice during pregnancy. It is generally considered safe.
- C. CORRECT. Warfarin crosses the placenta and is a known teratogen, especially during weeks 6-12 of the first trimester. It causes fetal warfarin syndrome. Warfarin is absolutely contraindicated in the first trimester.
- D. INCORRECT. Heparin does not cross the placenta (large molecule) and is the SAFE anticoagulant of choice during pregnancy. It is NOT contraindicated.