A 32-year-old woman with focal epilepsy is on carbamazepine. She becomes pregnant. The neurologist is most concerned about a specific teratogenic risk. Which neural tube defect is most strongly associated with carbamazepine use during the first trimester?

• A Spina bifida (myelomeningocele) ✓
• B Anencephaly
• C Holoprosencephaly
• D Dandy-Walker malformation

Explanation

Carbamazepine is associated with a 1-2% risk of spina bifida (myelomeningocele) when taken in the first trimester, related to folate antagonism and impaired neural tube closure. Valproate carries an even higher risk (~1-3%) of the same defect plus facial dysmorphism. Anencephaly can result from severe folate deficiency but is not specifically linked to carbamazepine. Holoprosencephaly and Dandy-Walker malformation are not characteristic carbamazepine teratogenic effects.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.