Antiepileptic drug exposure and major congenital malformations: the role of pregnancy registries.

The use of antiepileptic drugs (AEDs) in pregnancy is associated with an increased risk of fetal malformations. Although it is known that AEDs may differ with respect to the type of malformations they can induce, earlier studies have generally lacked the power to demonstrate differences between AEDs in their overall teratogenic potential. Furthermore, there is an urgent need to assess the clinical teratogenic potential of the newer-generation AEDs. Epilepsy and pregnancy registries have been established to provide such information, which is essential for the rational management of women with epilepsy with childbearing potential. The registries also provide opportunities for additional studies of seizures observed during pregnancy and labor and, with the enrolled woman's consent, for separate studies on cognitive outcomes and pharmacogenetics. Although most are prospective, the existing registries vary somewhat in design, which needs to be considered when their results are compared. Some registries are driven by pharmaceutical companies (often compelled by national or international drug licensing agencies) and provide data on pregnancy outcome related to the sponsor's own product. Others are organized by independent research groups and are potentially more useful in that they publish comparative data. This review provides a critical discussion and comparison of important methodological aspects of AED and pregnancy registries along with a summary of results published so far.