Fig. 1

Flow chart for the selected participants. We used data from 104,062 pairs of pregnant women and fetuses, including multiple births. Of these, the Kyoto Scale of Psychological Development 2001 (KSPD) was administered to participants in the sub-cohort at age two years, yielding data on 4,988 pairs. After excluding invalid KSPD results, multiple births, and those with missing data related to exposure and covariates, we finally analyzed 3,786 pairs.