Characteristics of the study participants.

The relationship between maternal prenatal psychological distress and epilepsy development in offspring has not yet been clarified. Herein, we used a dataset obtained from the Japan Environment and Children’s Study, a nationwide birth cohort study, to evaluate the association between six-item Kessler Psychological Distress Scale (K6) scores and epilepsy among 1–3 years old. The data of 97,484 children were retrospectively analyzed. The K6 was administered to women twice: during the first half (M-T1) and second half (M-T2) of pregnancy. M-T1 ranged from 12.3–18.9 (median 15.1) weeks, and M-T2 ranged from 25.3–30.1 (median 27.4) weeks. Participants were divided into six groups based on K6 scores of two ranges (≤4 and ≥5) at M-T1 and M-T2. The numbers of children diagnosed with epilepsy at the ages of 1, 2, and 3 years were 89 (0.1%), 129 (0.2%), and 149 (0.2%), respectively. A maternal K6 score of ≥5 at both M-T1 and M-T2 was associated with epilepsy diagnosis ratios among 1-, 2-, and 3-year-old children in the univariate analysis. Moreover, multivariate analysis revealed that a maternal K6 score of ≥5 at both M-T1 and M-T2 was associated with epilepsy diagnosis ratios among 1-, 2-, and 3-year-olds. Continuous moderate-level maternal psychological distress from the first to the second half of pregnancy is associated with epilepsy among 1-, 2-, and 3-year-old children. Hence, environmental adjustments to promote relaxation such as mindfulness in pregnant women might be necessary.