2.1. Data sources
This cross-sectional survey collected data on thromboembolism in
pregnancy from January 1 to December 31, 2019. Participating hospitals
included those across all levels that provided maternal healthcare
services in mainland China. Based on the Chinese national network of
women’s and children’s health, a survey request was sent to the chief of
the Department of Obstetrics of each hospital. Hospitals that completed
the survey and signed informed consent before February 29, 2020 were
enrolled for the final analysis, and those with missing data were
excluded. The Institutional Review Board of the Obstetrics and
Gynecology Hospital of Fudan University approved the project, and
written informed consent was obtained from each participating hospital
before enrollment.