1. Department of Obstetrics and Gynaecology; Nanfang Hospital; Southern Medical University; Guangzhou China
2. OMNI Research Group; Department of Obstetrics and Gynaecology; University of Ottawa Faculty of Medicine; Ottawa ON Canada
3. Clinical Epidemiology Program; Ottawa Hospital Research Institute; Ottawa ON Canada
4. McLaughlin Centre for Population Health Risk Assessment; Institute of Population Health; University of Ottawa; Ottawa ON Canada
5. Risk Sciences International; Ottawa ON Canada
6. Department of Epidemiology and Community Medicine; University of Ottawa; Ottawa ON Canada
7. Department of Medicine; Faculty of Medicine; University of Ottawa; Ottawa ON Canada
8. School of Public Health; Central South University; Changsha China