Published on in Vol 7, No 1 (2021): January
Preprints (earlier versions) of this paper are
available at
https://preprints.jmir.org/preprint/25241, first published
.
1 School of Medicine, Macau University of Science and Technology, Macau, China
2 Department of Epidemiology and Biostatistics, School of Public Health, Peking University, Beijing, China
3 Department of Obstetrics and Gynecology, Maternal and Child Health Hospital of Tongzhou District, Beijing, China