All old-generation antiepileptic drugs (AEDs) are considered to be teratogenic. In Germany, one out of 200 pregnant women (0.5%) is treated with AEDs for epilepsy. The risk of major malformations following exposure to AEDs during the first trimester of pregnancy is two to three times the rate reported in the general population, which is estimated at 2-3%. The risks associated with the treatment of epilepsy during pregnancy are therefore of major concern to all women of childbearing potential with epilepsy. Data on the comparative teratogenicity of these AEDs in humans are, however, conflicting, mainly due to inadequate sample sizes and other methodological shortcomings of previous studies. The teratogenic potential of newer AEDs is even less well known, which prevents a rational approach to AED treatment in women of childbearing potential. The European Registry of Antiepileptic Drugs and Pregnancy is a prospective international multicentre study of pregnancies with AEDs. In Germany the project was started in 2001 and so far more than 500 pregnancies have been enrolled. The enrollment rate is 4% of 4,000 pregnancies with AEDs reported annually.