Data collection
We used seven types of data from the dataset released in March 2018 (jecs-an-20180131) that included information from questionnaires and medical record transcripts. MT1 provided data from self-reported questionnaires collected during the first trimester that included information about maternal medical backgrounds. DrT1 provided medical information collected from the medical record transcripts during the first trimester provided by each co-operating health care provider. MT2 provided data from self-reported questionnaires collected during the second/third trimester that included information on lifestyle and socioeconomic status. Dr0m provided perinatal information collected from the medical record transcripts provided by each co-operating health care provider. M1m provided data from self-reported questionnaires collected at one month after birth. C6m provided data from self-reported questionnaires collected at six months after birth. C1Y provided data from self-reported questionnaires collected at 12 months after birth. We excluded women who miscarried, had multiple births, whose babies were stillborn, or whose data regarding confounders were missing (Fig. 1).