Phenytoin (or Dilantin) is a medication used to treat epilepsy (seizure disorder). If taken by the mother in the first trimester, there is a small chance for a combination of birth defects known as the Fetal Hydantoin Syndrome, and that the baby will be born with some of the following health problems:
Dilantin crosses the placenta in such a way that the developing fetus receives a much higher dose of the medication than the mother is taking (the drug is metabolized differently). This is especially true when the medication is used during the first trimester of pregnancy.
When a woman with epilepsy is planning a pregnancy, it is important for her to meet with both her neurologist and her obstetrician before conception, to discuss the specific treatment to be used to control seizures while pregnant.