A recent study conducted at 25 epilepsy research centers in the United States and Britain, including USC, found that young children exposed to a common epilepsy drug in utero had lower I.Q. scores than those whose mothers took a different antiseizure medication.

The study was published last month in the New England Journal of Medicine.

“We can now say that valproate should not be the first line treatment for pregnant women with epilepsy,” said Laura Kalayjian, M.D., assistant professor of neurology at the Keck School of Medicine and co-director of the USC Epilepsy Center. “Previous research has shown that the drug increased the risk of birth defects, but we can now confirm that cognitive defects are associated with exposure in utero.”

Valproate is a drug commonly used to treat epilepsy as well as migraines and psychiatric disorders.

The study looked at cognitive outcomes in children at 3 years of age after exposure to different antiepileptic drugs in utero. The researchers found that children whose mothers had taken valproate during pregnancy had I.Q. scores that were nine points lower on average than children who had been exposed to the epilepsy medication lamotrigine. I.Q. scores were also lower compared to children whose mothers had taken the antiseizure drugs carbamazepine and phenytoin.

The study enrolled 303 pregnant women who were using any of several antiepileptic drugs from October 1999 to 2004. Cognitive assessments were conducted in 258 children at 2 and 3-years of age. Of these children, 73 had been exposed to valproate. Researchers found that children's I.Q. scores were significantly related to the mother's I.Q. scores among those exposed to other drugs, but not among children exposed to valproate.

The USC Epilepsy Center was the only California research center involved in the study, and enrolled 26 of the children studied, including one set of twins. Many of the mothers were recruited from a specialized Neurology High Risk Obstetrics clinic at LAC + USC Medical Center, Kalayjian said. USC researchers are still in the process of collecting data on these children since the final outcome of the study will be IQ at age 6, A follow up study with similar design evaluating several newer anti-seizure medications is being planned.

“We now have data regarding long term effects of antiepileptic drug use during pregnancy and can inform patients planning to conceive,” she said. “Since approximately 50 percent of pregnancies in the U.S. are unplanned, clinicians should be wary of prescribing Valproate for any condition to women of child bearing