Pregnant women taking valproate, a drug used to treat epilepsy, may significantly increase their baby’s risk of developing autism, according to a study published in the Dec. 2 issue of the journal Neurology.

The study is still in its preliminary stage. That’s why “women shouldn’t suddenly stop taking their medication because they read this study. The consensus has always been that having convulsions is worse than the medication, so if a medication is needed to prevent seizures, it should be continued,” says Michael Goldstein, MD, a fellow of the American Academy of Neurology.

The study involved 632 children, half of whom had a mother with epilepsy. Of those children, 64 were exposed to valproate in utero, 44 lamotrigine, 76 to carbamazepine, and 65 to other epilepsy drugs or combinations of drugs. Forty-seven children were not exposed to any antiseizure drugs. The children were tested for autism at ages 1, 3, and 6.

The children whose mothers were taking valproate alone for epilepsy were seven times more likely to develop autism, compared to children whose mothers did not have epilepsy and were not taking any drug while pregnant, the study shows. None of the children in the study had any known family history of autism.

The take home message from this study is that “women who take valproate while pregnant should be informed of the possible risks of autism and are encouraged to discuss them with their doctors,”

Previous studies have linked epilepsy drugs with an increased risk of birth defects, such as spina bifida (a defect of the spinal cord) and heart malformations. This is the first study to link the drug to autism.

Autism is a disorder that affects the development of the brain. How this occurs is not yet understood. The disease involves impaired social interaction and communication, as well as restricted and repetitive behavior, all starting before one’s third birthday. Starting the 1980s, the number of autism cases has increased significantly. As maintained by the Centers for Disease Control and Prevention, about 1 in every 150 children has autism or a related disorder.