Link Between Antiseizure Medications and Birth Defects During Pregnancy

A recent study published in the journal Neurology on July 16, 2025, has identified a concerning link between specific antiseizure medications and an increased risk of birth defects when taken during pregnancy. The research, conducted by a team led by Dr. Sonia Hernandez-Diaz, MD, DrPH, from the Harvard T.H. Chan School of Public Health, analyzed data from 7,311 women who used antiseizure medications in their first trimester and compared their outcomes to 1,311 women who did not use such medications.

Seizures pose significant risks to pregnant women, including falls and other complications, making effective seizure control crucial for the health of both the mother and child. Historical data has indicated that some older antiseizure drugs are associated with major malformations; however, the safety profiles of newer 'second-generation' medications have been less understood. This study sheds light on the differential risks associated with various antiseizure medications.

Among the medications examined, valproate presented the highest risk, with 9% of infants exposed to it exhibiting major birth defects. This was followed by phenobarbital at 6% and topiramate at 5%. In contrast, lamotrigine, used as a reference group, had a birth defect occurrence of only 2%. Notably, the research revealed that mothers who took valproate had more than five times the risk of having a child with major malformations compared to those who took lamotrigine. Similarly, phenobarbital users faced nearly three times the risk, while topiramate users presented over twice the risk.

Dr. Hernandez-Diaz emphasized the importance of this research for healthcare providers and prospective parents, stating, "Our results confirm that using valproate, phenobarbital, or topiramate during early pregnancy is linked to a higher chance of major birth defects in the infants when compared to lamotrigine." However, it was also noted that medications such as levetiracetam, oxcarbazepine, gabapentin, and zonisamide did not show an increased risk of malformations. The data regarding lacosamide and pregabalin was inconclusive, indicating the need for further research.

A limitation of the study was the timing of participant enrollment, which was months after conception, potentially leading to an underestimation of birth defect occurrences as early pregnancy losses were not included in the assessment.

The findings of this study carry significant implications for pregnant women with epilepsy and their healthcare providers. As Dr. Hernandez-Diaz concludes, understanding the risks associated with these medications is vital for making informed decisions about seizure management during pregnancy. Additionally, this research underscores the necessity for ongoing studies to clarify the safety profiles of newer antiseizure medications and to guide clinical practices effectively.