Study design
We performed a retrospective case–control study, using data on all prenatal visit and discharges from Shanghai First Maternity and Infant Hospital for the period of January 1st, 2017 to July 31th, 2021 to evaluate the effect of maternal weight gain in different periods of pregnancy on VTE at any site. Written informed consent was obtained from the participants. The data including maternal demographical characteristics, reproductive history, as well as clinical information related to this pregnancy were collected. This study was approved by Ethics Committee of Shanghai First Maternity and Infant Hospital (reference number: KS2057).