Pregnancy and epilepsy:update on pregnancy registries.

In the United States, about 1 million women of childbearing age have epilepsy. Estimates vary as to the percentage of these women who consider pregnancy, but epilepsy is the most common neurologic condition encountered in pregnancy. Women with epilepsy express significant interest in receiving guidance about pregnancy and the effects of seizures and anticonvulsant treatments on the developing fetus, but clinicians often are hard-pressed to find accurate and relevant information to share. In our practice, we devote many hours of clinical time to the counseling required when such a request is made. We begin by providing information about the risks of pregnancy for any woman, comparing the data for women with and without epilepsy; this gives patients perspective on the increase in the risk of fetal malformations associated with anticonvulsant therapy. We then proceed with an evaluation of whether the patient could consider withdrawing one or more anticonvulsants, particularly during the first trimester of gestation. For women who must continue taking anticonvulsants to prevent seizures, we explain that the increase in metabolism during pregnancy will require an increase in oral dosing to maintain prepregnancy concentrations of anticonvulsants. It is hoped that by maintaining prepregnancy blood levels during pregnancy, a woman with epilepsy can maintain the same level of seizure control during pregnancy that she had before conception. Additional time is spent discussing the need for adequate hydration, regular meals, and proper sleep during pregnancy and in the postpartum time to avoid behavioral alterations that can trigger seizures. As seizure medicines will need to be decreased after delivery, when a patient will be sleep-deprived and under the influence of hormonal changes that can increase the seizure tendency, our nurses meet with patients throughout pregnancy to develop plans for partner or family assistance with care of the neonate. Patients report appreciation for this type of personalized counseling but express frustration that we cannot provide absolute guidance with respect to the use of anticonvulsants in pregnancy. Therefore we often have to return several times to the topic of the limitations of scientific research regarding decision-making in pregnancy. Much of the information we have about the safety of anticonvulsant use in pregnancy comes from the registry studies discussed in this article. These studies can be difficult to interpret and compare because of the diversity of the methods used.