1. Key Laboratory for Major Obstetric Diseases of Guangdong Province; Department of Obstetrics and Gynecology; Third Affiliated Hospital of Guangzhou Medical University; Guangzhou Medical Centre for Critical Pregnant Women; Guangzhou China
2. OMNI Research Group; Department of Obstetrics and Gynecology; Faculty of Medicine; University of Ottawa; Ottawa ON Canada
3. Clinical Epidemiology Program; Ottawa Hospital Research Institute; Ottawa ON Canada
4. Public Health Agency of Canada; Ottawa ON Canada
5. BORN Ontario; Ottawa ON Canada
6. School of Epidemiology and Public Health; Faculty of Medicine; University of Ottawa; Ottawa ON Canada