Pregnancy may be especially problematic for the epileptic woman, obstetric complications tend to be more frequent, and seizure control and the pharmacokinetics of anticonvulsants may be affected. The risk of seizures is particularly high during labour and delivery-almost 10-fold higher than at other times during pregnancy. As uncontrolled generalised tonic-clonic seizures may be hazardous to both gravida and fetus, the use of anticonvulsants to prevent their occurrence is to be recommended during pregnancy even though all anticonvulsant drugs are potential teratogens. There is a 2- to 3-fold increase in the risk of birth defects in conjunction with fetal exposure to these drugs. Although the mechanisms mediating the teratogenic effects have not been identified, interference with folate metabolism, formation of toxic metabolites and drug-induced fetal hypoxia have been suggested. Despite the incompleteness of our knowledge, some recommendations can be made for the management of pregnant women with epilepsy. Pre-pregnancy counselling is important. Epileptic women contemplating pregnancy need to be informed of the pros and cons, and any major change in anticonvulsant therapy should be made before conception. Monotherapy is preferable, using the drug appropriate to seizure type and epilepsy syndrome at the lowest dosage and serum level that protects against tonic-clonic seizure. The clinical situation needs to be assessed and drug levels need to be monitored more frequently during pregnancy than otherwise. Patients on anticonvulsant treatment during pregnancy also need to be informed of the possibility of antenatal diagnosis. The use of new anticonvulsant drugs during pregnancy represents a particular challenge, since available clinical data may be insufficient to indicate their teratogenic potential Such a drug should be used in pregnancy only if essential to obtain seizure control. Moreover, the outcome of all such pregnancies needs to be carefully documented.