Children born to women who took the epilepsy drug Depakote while pregnant had lower IQ scores than those whose moms took three other antiseizure meds, research published  this week shows. The results suggest that women of childbearing age should only use Depakote as a last resort,  the American and British study authors say.

The average IQ among three-year-olds whose mothers took Depakote (chemical name valproate) was 92, compared with 101 for children exposed in utero to lamotrigine, 99 among kids whose moms took phenytoin and 98 for children whose mother took carbamazepine, according to the study in this week's New England Journal of Medicine. The results are based on 309 children being followed at 25 epilepsy centers in the U.S. and the United Kingdom.

Kids' IQs were closely related to their moms' intelligence except among children exposed to Depakote, "a result suggesting that valproate disrupted this normally robust relationship," according to the study.

Prescribing information for Depakote warns that it can cause birth defects including spina bifida (incomplete closure of the spine in utero that can cause paralysis and learning disabilities) and malformations of the heart and skull. It says the drug should only be used in women of childbearing age if the benefits outweigh the risks to a developing fetus. "For many women, Depakote may be the only effective medicine to control their seizures, but it is important that physicians and patients have a candid conversation about the risks of treatment versus the benefits of treatment," manufacturer Abbott told WebMD.

More than half of prescriptions for antiseizure meds are written for patients with disorders other than epilepsy, the study notes, such as migraine and bipolar illness.

Two registries of pregnant women who are taking antiseizure drugs—the North American Antiepileptic Drug Pregnancy Registry and the International Registry of Antiepileptic Drugs and Pregnancy—are collecting information about why the meds cause the effects they do and which ones may be safer during pregnancy.

Image © iStockphoto/Olivier Lantzendörffer