Women who may become pregnant should be aware that studies have suggested a connection between phenobarbital and a higher-than-expected incidence of birth defects.

There also is a danger to the baby from withdrawal symptoms if the mother has taken phenobarbital in the last few months of pregnancy, since barbiturates like phenobarbital cross the placenta into the baby.

Communicate with your doctor about the potential effects of phenobarbital if you are pregnant or plan to become pregnant. Since phenobarbital reduces the effectiveness of oral contraceptives (birth control pills), you should be especially cautious.

Reviewed February 2004 by Steven C. Schachter, MD, epilepsy.com Editorial Board.