From the FDA
The U.S. Food and Drug Administration (FDA) is informing the public of new data that show that there is an increased risk for the development of cleft lip and/or cleft palate (oral clefts) in infants born to women treated with topiramate (Topamax and generic products) during pregnancy.
The benefits and the risks of topiramate should be carefully weighed when prescribing this drug to women of childbearing age, particularly for conditions not usually associated with permanent injury or death. Alternative medications that have a lower risk of oral clefts and other adverse birth outcomes should be considered for these patients. If the decision is made to use topiramate in women of childbearing age, effective birth control should be used. Oral clefts occur in the first trimester of pregnancy before many women know they are pregnant.
Topiramate was previously classified as a Pregnancy Category C drug, which means that data from animal studies suggested potential fetal risks, but no adequate data from human clinical trials or studies were available at the time of approval. However, because of new human data that show an increased risk for oral clefts, topiramate is being placed in Pregnancy Category D. Pregnancy Category D means there is positive evidence of human fetal risk based on human data but the potential benefits from use of the drug in pregnant women may be acceptable in certain situations despite its risks.