Which cytotoxic agent is particularly teratogenic and requires strict contraception and pregnancy testing?

• A. Vincristine
• B. Paclitaxel
• C. Cyclophosphamide
• D. Methotrexate

Answer: (D)

Teratogenicity with cytotoxic chemotherapy requires careful pregnancy planning, and one drug is widely recognized for needing strict contraception and regular pregnancy testing because of its high fetal risk. Methotrexate blocks dihydrofolate reductase, disrupting DNA synthesis and cell replication. This hits rapidly dividing fetal cells hard, leading to serious congenital anomalies or fetal loss if exposure occurs during pregnancy. Because of that risk, contraception is mandatory during treatment and for a period after stopping, and pregnancy tests are required before each cycle to ensure the patient isn’t pregnant. Other agents may carry fetal risks, but methotrexate is the classic drug for which ongoing pregnancy screening and contraception are emphasized due to its pronounced teratogenic potential.