To evaluate the relationship between periconceptional folate supplementation and pregnancy outcomes in patients with epilepsy (PWE).

Folic acid supplementation is well-established to prevent neural tube defects in PWE taking anti-seizure medications (ASMs). The real-world implementation and effectiveness of this practice warrant ongoing evaluation.

This was a retrospective cohort study of pregnant PWE who received care at an urban tertiary care center from August 2013 to May 2025. Data extracted included maternal demographics, epilepsy history, ASMs, periconceptional folic acid dosage, and neonatal/pregnancy outcomes. Folic acid supplementation was categorized as: no periconceptional supplementation, 1 mg/day, 2+ mg/day.

We identified 165 pregnancies (142 unique patients) with outcomes from 199 pregnancies in our cohort. The average age of our cohort was 26 years, and 64.8% of our cohort did not take periconceptional folic acid.  Based on a multiple regression model on 108 pregnancies that had all data points, periconceptional folic acid (p=0.139), maternal age (p=0.472), and the number of ASMs (p=0.460) were not significant predictors of birth weight. As expected, gestational age had the most significant impact (p<0.001) on birth weight, with each additional week of gestation associated with a 181-gram increase in birth weight. A regression analysis of predictors of periconceptional folic acid use revealed that higher education (some college or more; p=0.029) and having a planned pregnancy (p=0.001) were significant. Insurance type (p=0.396) and maternal age (p=0.117) were not significant predictors of taking periconceptional folic acid.

Our findings highlight a critical gap in patient education and clinical practice. There is a continued need to educate patients of childbearing potential with epilepsy on the importance of pregnancy planning and periconceptional folic acid supplementation. A larger cohort and more granular data to elucidate why folic acid is not taken may drive further interventions.