Data collection
The current analysis used the data set released in June 2016 (data set:
jecs-ag-20160424). Specifically, we used three types of data: (1) M-T1,
obtained from a self-reported questionnaire that was collected during
the first trimester (the first questionnaire) and included questions
regarding maternal medical background; (2) M-T2, obtained from a
self-reported questionnaire that was collected during the second or
third trimester (second questionnaire) and included questions regarding
lifestyle and socioeconomic status; and (3) Dr-0m, collected from the
medical records’ transcripts provided by each participant’s institution
and that included obstetrical outcomes such as gestational age, birth
weight, neonatal sex, and maternal body weight. The participants with
singleton pregnancies after 22 weeks were included in the present study.
The women with missing information were excluded from the analysis.