The U.S. Food and Drug Administration (FDA) lists Topamax (topiramate) in Pregnancy Category C. This indicates that caution is advised, but the benefits of the medication may outweigh the potential risks. There have been no well-controlled studies in women, but studies in animals have shown some harm to the fetus.

The babies of women taking seizure medicines in general have a greater than usual number of major birth defects like cleft lip, cleft palate, and heart malformations. Defects like these occur in 2-3% of all pregnancies but affect 4-7% of the babies of women taking seizure medicines. Whether this is also true for Topamax is not yet known.

In general, the risk of defects is higher for women who take more than one AED and for women with a family history of birth defects.

Women who are capable of becoming pregnant should take at least 400 mcg (0.4 mg) of folic acid (folate) daily to help prevent a type of birth defect called a neural tube defect. (The best-known of these is spina bifida, in which the spinal cord is not completely enclosed.) Women at high risk, such as those with a history of this kind of defect in a previous pregnancy, should take 4000 mcg (4 mg) daily, beginning before they become pregnant.

About 20% to 35% of women have seizures more often during pregnancy because of changes in hormones or changes in how their seizure medicine is handled by the body. Whether this applies to Topamax is not known, so the doctor may recommend checking the level of Topamax in the blood regularly during pregnancy so that the dosage can be adjusted as needed.

There is limited information on how much Topamax is passed through breast milk. The potential for serious side effects in nursing infants is unknown. Mothers who are considering breast-feeding while taking Topamax should discuss the options with their doctor. See the package insert for more details.

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