Early Folic Acid Supplementation May Halve the Risk of Birth Defects in Women Using Antiseizure Medication

This study suggests that starting high-dose folic acid before pregnancy could significantly reduce the risk of birth defects in women taking antiseizure medications for epilepsy. Researchers found that women who began supplementation one to twelve weeks prior to conception had about a 45 percent lower risk of major congenital anomalies compared to those who did not take high-dose folic acid. In contrast, starting supplementation after pregnancy had already begun showed no protective effect, highlighting the importance of timing.

The study analyzed more than 13,000 pregnancies across Denmark, Norway, Sweden, and Iceland. Among women not taking high-dose folic acid, around 48 in every 1,000 pregnancies resulted in congenital anomalies, compared to 26 per 1,000 when supplementation was started before pregnancy – an absolute reduction of 22 cases per 1,000. The protective effect was even stronger in women using higher-risk antiseizure drugs such as valproate, where risk reductions of up to 86 percent were observed.

Published in the Journal of Neurology, Neurosurgery & Psychiatry, the findings help clarify longstanding uncertainty about folic acid use in this context, particularly the importance of beginning supplementation before conception.

To read about research suggesting that vitamin D may be a safe, seizure-minimizing epilepsy treatment, see this news story on our website.