As per ACOG and RCOG guidelines, there is no particular drug of choice for epilepsy in pregnancy Valproate increases chances of birth defects much more than phenytoin, carbamazepine or phenobarbitone and hence if valproate is being used, it should be substituted by a lesser teratogenic drug. Now in this question: A 26-year-old primigravida with juvenile myoclonic epilepsy who has been using valproic acid comes to you at fourth month of pregnancy for advice. Logically speaking if patient has myoclonic epilepsy in non pregnant states-DOC is valproic acid —Harrsion 18/e, p 3266 or lamotrigine, so her physician must have prescribed valproic acid to her. Ideally valproic acid should not be used during pregnancy as it is associated with a high risk of congenital malformations in the fetus. So if this patient would have come in the first trimester, I would have substituted it with some other antiepileptic drug like lamotrigine.