The bad news is about the drug valproic acid. One study monitored the rate of birth defects in infants whose mothers had taken valproic acid as their only epilepsy drug during the first trimester of pregnancy and were enrolled in the North American Antiepileptic Drug (AED) Pregnancy Registry. Of the 149 women in the study, there were 16 infants with birth defects, or 10.7 percent. The women taking valproic acid were nearly three times more likely to have an infant with a birth defect than women taking another epilepsy drug. They were more than seven times more likely to have an infant with a birth defect than women in the general population.
For the second study on valproic acid, British researchers recruited 163 mothers with epilepsy and their children and gave them a number of tests. A total of 249 children between the ages of 6 and 16 took the tests. The 41 children who were exposed to valproic acid during pregnancy were more likely to have low verbal IQ scores (average of 84) compared to other groups in the study, such as those exposed only to the drug phenytoin (average score of 99) or those not exposed to any epilepsy drug during pregnancy (average score of 92).
Those exposed to valproic acid were also more likely to have overall IQ scores in the extremely low, or mentally impaired, range. Two to three percent of the population would be expected to fall in this range. In the study, 22 percent of those exposed to valproic acid were in this range.
Penovich noted that maintaining effective epilepsy treatment during pregnancy is crucial. "Seizures can cause fetal distress, and the severe epilepsy state called status epilepticus where attacks occur in rapid succession may cause catastrophic damage to the brain of the fetus," she said. More studies must be done to understand how valproic acid works to affect fetal development. "Without good animal models, the mechanism for the abnormalities remains unknown," Penov
Contact: Marilee Reu
American Academy of Neurology