Effects of antiseizure medication withdrawal during the first trimester of pregnancy on seizure control and offspring outcomes

Objective: To explore seizure control and offspring outcomes associated with antiseizure medication (ASM) withdrawal during the first trimester of pregnancy. Methods: Based on a prospective multicenter study in China, pregnancies followed up between 2009 and 2023 at the neurology outpatient clinic of 50 hospitals were included in this study. Information on demographics, epileptic characteristics, treatment during pregnancy, and offspring outcomes was collected. Pregnancies were categorized into an ASM withdrawal group and an ASM continuation group. Balance tests and univariate log- binomial regression analysis were conducted to identify imbalanced factors between groups and potential risk factors for seizure deterioration during pregnancy. Multivariate log- binomial regression was then used to estimate the adjusted effects of ASM withdrawal on seizure deterioration during pregnancy and fetal outcomes. In addition, exploratory subgroup analysis was conducted to identify high- risk patients who should avoid ASM withdrawal. Results: Of the 695 pregnancies enrolled, 14.2% withdrew ASMs in the first trimester of pregnancy. ASM withdrawal during this period was associated with a risk of seizure deterioration during pregnancy (adjusted risk ratio [aRR] 1.405, 95% confidence interval [CI] 1.009-1.876). Subgroup analysis revealed a significant risk of seizure deterioration in pregnancies with seizures in 9 months (aRR 1.590, 95% CI 1.079-2.344). After adjusting the folic acid dose, no evidence of protective effects on fetus after ASM withdrawal was observed compared to patients with continued treatment, whereas seizure deterioration during pregnancy increased the risk of fetal death (aRR 3.577, 95% CI 1.086-11.651). Significance: ASM withdrawal in the first trimester of pregnancy did not show a protective effect on fetal outcomes but rather resulted in increased seizure frequency during pregnancy. However, this finding requires a larger sample for validation. Furthermore, seizure deterioration during pregnancy was associated with an increased risk of fetal death.