Drugs for epilepsy have teratogenic risks

Editor—We would like to draw attention to the fact that no anticonvulsant has been shown to be without risk to the fetus in pregnancy.¹ Associations with neural tube defects and facial clefts are well recognised, but congenital abnormalities alone are a crude indicator of teratogenicity. Of increasing concern is the risk of intellectual impairment, which is frequently only apparent in later childhood. Several studies that include long term follow up are currently under way.

We recognise that anticonvulsant treatment during pregnancy is unavoidable for many women, for whom attempts should be made to achieve control with the fewest agents and lowest dose possible. Nevertheless, we also recognise that many women of childbearing age, despite being seizure free for several years, continue to take anticonvulsants rather than risk losing their driving licence should a seizure occur when treatment is withdrawn. These women are unable to make informed decisions unless they are fully aware of the teratogenic risks of their treatment.

More subtle effects of exposure to anticonvulsants in utero are increasingly recognised, frequently by developmental paediatricians and clinical geneticists.²,³ The experience with newer anticonvulsants is limited.⁴ Failure to appreciate the risk of neurological impairment to the fetus by clinicians prescribing anticonvulsants and providing preconceptional advice can mislead parents. Indeed, we are aware of several instances where this omission has resulted in litigation.