Newer Antiseizure Medications During Pregnancy May Pose Less Risk Than Older Drugs

A recent study published in the journal Neurology has provided new insights into the safety of antiseizure medications used during pregnancy. The research examined both older (first-generation) and newer (second-generation) anticonvulsant drugs to determine their associated risks of birth defects when taken during the first trimester.

The study involved 7,311 women who took antiseizure medications during early pregnancy, compared to 1,311 women who did not take such drugs. Participants were interviewed multiple times—at the beginning of pregnancy, at about seven months, and within three months after delivery. Medical records confirmed the presence of birth defects, which included cleft lips, congenital heart holes, neural tube defects such as spina bifida, limb deficiencies, and other structural abnormalities.

Results showed that certain medications carry higher risks of birth defects. Valproate had the highest association, with about 9% of infants exposed developing major malformations. Phenobarbital was linked to a 6% risk. Among newer drugs, topiramate was associated with a 5% incidence of birth defects, whereas lamotrigine was linked to a 2% rate. When compared directly to lamotrigine, valproate increased the risk of birth defects over fivefold, phenobarbital nearly tripled the risk, and topiramate more than doubled it.

These findings suggest that some newer antiseizure medications, such as levetiracetam, oxcarbazepine, gabapentin, and zonisamide, may be safer options during pregnancy, as they did not show an increased risk of major birth defects. However, for drugs like lacosamide and pregabalin, the data was insufficient to draw definitive conclusions, calling for further research.

The researchers acknowledged a limitation in their study: participants were enrolled months after conception, meaning early pregnancy losses and associated malformations might have been underreported. Nonetheless, the study emphasizes the importance of carefully selecting antiseizure medications for women who are pregnant or planning pregnancy, to reduce the risk of birth defects while effectively managing seizures.

According to Sonia Hernandez-Diaz, MD, DrPH from Harvard T.H. Chan School of Public Health, "Seizure control is critical during pregnancy, but safety of medications is equally important. Our study helps inform healthcare providers and women about the potential risks associated with different anticonvulsants to support safer choices."

For more details, the full study can be accessed through Neurology: doi: 10.1212/WNL.0000000000213786.