Our results have shown a significant decrease in the prevalence of major malformations, as compared with the previous study: 8.8% vs. 24.1% (P $<$ 0.01). Monotherapy was more frequent and the mean number of drugs used during pregnancy was significantly smaller in the present study. Phenytoin, phenobarbital and primidone were prescribed less frequently in the present study, whereas carbamazepine and valproic acid were used more frequently. Plasma levels of valproic acid during pregnancy were higher in mothers of malformed babies. In the present study, plasma folate levels were significantly higher, and more patients were taking folate supplements during pregnancy.