BOSTON Birth defects such as a small head or growth retardation seen in the babies of epileptic women who take drugs for their seizures are caused by the drugs, not the epilepsy, researchers reported in ***New England Journal of Medicine***.

According to Reuter, Dr. Lewis Holmes of the Massachusetts General Hospital and his colleagues found that 98 women with epilepsy who did not take anti-seizure drugs during their pregnancy were no more likely to have a baby with a physical deformity than 508 women without epilepsy.

But among 316 women who took a drug such as phenobarbital, or phenytolin, sold under the brand name Dilantin and made by Pfizer Inc.'s Parke-Davis Unit, or the drug carbamazepine, sold under the brand name of Tegretol by Novartis AG the rate of birth defects was nearly three times higher.

And for women who took two or more of the anti-seizure drugs, the rate was more than four times higher.

The malformations included a small head, growth retardation, and abnormalities of the face and fingers.

Some medical textbooks have attributed such malformations to the seizures themselves or genetic abnormalities that put the mother at risk for epilepsy, the researchers said.

"We also found that infants of women who had taken anticonvulsant drugs as treatment for mood disorders, migraine, or pain had an increase" in the frequency of defects, a pattern "that was similar to that among infants of women with epilepsy," Holmes and his colleagues reported.