Analysis based on information provided by the International Registry of Antiepileptic Drugs and Pregnancy found that the incidence of malformations with four antiepileptic drugs, carbamazepine, valproic acid, lamotrigine, and phenobarbital, increased significantly with increasing drug dose. Low-dose lamotrigine was the least teratogenic, 2.0% (<300 mg) and 4.5% (≥300 mg); carbamazepine was the second least teratogenic, 3.4% (<400 mg) and 5.3% (≥400 mg, <1000 mg), and the results suggest that low-dose lamotrigine is the safest choice for pregnant patients with epilepsy, followed by low-dose carbamazepine.