A new Norwegian study has found that  children of women who take drugs to treat epilepsy during pregnancy may be at increased risk for physical and mental developmental delays early in life.

The researchers found that 333 of the children were exposed to anti epileptic drugs in the womb. At 18 months of age, these children were more likely to have motor skills problems and traits of autism. By 36 months of age, these children developed problems with sentence skills as well as motor skills and autism.

The children exposed to anti epileptic drugs also had an increased risk of birth defects, according to the study appearing July 18 in the journal Epilepsia.

No physical or mental development delays were found in children born to women with epilepsy who did not take anti epileptic medication during pregnancy, and children of fathers with epilepsy generally showed normal early development, according to a journal news release.

“Our study … confirms that children exposed to anti seizure medications in the womb had lower scores for key developmental areas than children not exposed to [anti epileptic drugs],” concluded Dr. Gyri Veiby, of Haukeland University Hospital in Bergen, Norway, and colleagues. “Exposure to carbamazepine, lamotrigine, valproate or multiple anti seizure medications was linked to adverse developmental outcomes.”

The study’s  researchers stressed the importance of good seizure control during pregnancy that balances possible harmful effects on the baby’s brain development. Future studies should examine the effects of specific anti epileptic medications on fetal development and whether these effects continue on throughout  a child’s life.