Data collection
The current analysis used the JECS dataset released in June 2016 (dataset: jecs-ag-20160424). We used two types of data: (1) T1, comprising data obtained from the self-reported questionnaires collected during the first trimester (the first questionnaire), and included questions related to the maternal medical background; (2) M0, which included data for obstetric outcomes. These data were retrieved from the medical records provided by each cooperating health care provider. The participants with multiple-gestation pregnancies and those with missing data were excluded from the analysis.