In the United States, the Food and Drug Administration (FDA) assigns each medication to a Pregnancy Category according to whether it has been proven to be harmful in pregnancy. gabapentin is listed in Pregnancy Category C. This indicates that caution is advised, but the benefits of the medicine may outweigh the potential risks. Studies in animals have shown some harm to the baby, but there haven't been any good studies of results in women.
Talk to your doctor or another health professional if you are pregnant or plan to become pregnant. We don't yet have enough information to be able to estimate the risk of various types of birth defects that might occur if gabapentin is taken during pregnancy. We also don't know enough to compare the risk with gabapentin to the risk with other seizure medicines.
In general, the risk of defects is higher for women who take more than one seizure medicine and for women with a family history of birth defects. Whether this applies to gabapentin is not yet known.
All women who are capable of becoming pregnant should take at least 0.4 mg (400 mcg) of the vitamin called folic acid every day because it helps to prevent one type of birth defect. (The most well-known of these is spina bifida, in which the spinal cord is not completely enclosed.) If the doctor thinks a woman is at especially high risk, a much larger dose of folic acid—4 mg (4000 mcg) per day—may be recommended.
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. Even though this may not apply to gabapentin, the doctor may recommend checking the level of medication in the blood regularly during pregnancy so that the dosage can be adjusted as needed.
During breast-feeding, a small amount of the gabapentin will appear in the milk. The effect of this amount on an infant is unknown. If you are taking gabapentin and want to breast-feed your baby, check with your doctor about what seizure medicine would be best for you.