Phenytoin is a medicine used to treat seizures (epilepsy). But the medicine can cause birth defects if a woman takes it during pregnancy.
A baby born to a mother who took phenytoin has a 5 in 100 to a 1 in 10 chance of having a birth defect. This birth defect is a combination of problems called fetal hydantoin syndrome.
Babies with this syndrome may be born with some of the following health problems:
Delay in development
Certain facial features
Problems with the fingers and nails
Phenytoin travels to the developing baby through the placenta. But the developing baby gets much more of the medicine than the woman taking it. This is because the developing baby processes it differently than the woman does. This is especially true when the woman takes this medicine during the first trimester of pregnancy.
Despite these risks, it’s important for a woman with epilepsy to control her seizures while she’s pregnant. A woman with epilepsy should meet with her healthcare providers before becoming pregnant. She should see both her neurologist and her obstetrician to talk about how she should control seizures while pregnant.