Drugs, Pregnancy, and Lactation. (Antiepileptics).

An estimated 0.5%-2% of pregnant women are on antiepileptic medication. Most experts would agree that medical treatment of seizures cannot be stopped during pregnancy because of the high risks to the fetus if the mother has a seizure. The problem is that most first-line antiepileptic drugs have been associated with some degree of fetal risk, although the vast majority of exposed fetuses are not affected.

Some studies suggest epilepsy itself is associated with a higher risk of fetal malformations. Other research has come to different conclusions. A recent study following a relatively large group of untreated pregnant women with epilepsy suggested the disorder confers no increased fetal risk.

All three of the first-line drugs for treating epilepsy--carbamazepine (Tegretol), valproic acid (Depakote), and phenytoin (Dilantin)--have been associated with some fetal risks.

There are not much data yet on the safety of the new generation antiepileptics, such as lamotrigine (Lamictal) and gabapentin (Neurontin), when used during pregnancy.

When antiepileptics are combined, the rate of fetal malformations increases. Thus, when a woman is on more than one antiepileptic, she should be followed closely with detailed ultrasound. For a patient planning a pregnancy, clinicians should carefully consider whether she can be managed on fewer drugs before she conceives.

Here is a rundown on the risks associated with various antiepileptics:

* Valproic acid. This drug is associated with about a 2% risk of neural tube defects, which can be detected in utero with detailed ultrasound and alpha-fetoprotein measurement. There is a debate over whether valproic acid is associated with other malformations, such as limb deformities, but the evidence for this has not been strong.