Epilepsy is a common medical problem and many studies have demonstrated that infants of women with epilepsy (WWE) have a two to threefold higher risk of congenital malformations compared with the background population. The majority of WWE have normal, healthy children. However, WWE have an increased risk of congenital malformations. Congenital malformations are twice as common in infants exposed to antiepileptic drugs in utero. A variety of congenital malformations have been reported, with a particular preponderance of orofacial clefts. Valproate is often associated with the development of neural tube defects. In this review, we analyse the problem of neural tube defects and report in detail the main pathogenetic theories about the onset of this type of congenital malformation. There is strong evidence for a protective effect of adequate folate consumption.