1. Department of Epidemiology and Biostatistics, School of Public Health Tianjin Medical University Tianjin China
2. Department of Women Health, Tianjin Women and Children's Health Center Tianjin China
3. Nankai District Women and Children's Health Center Tianjin China
4. Heping District Women and Children's Health Center Tianjin China
5. Department of Medicine and Therapeutics, Hong Kong Institute of Diabetes and Obesity, Li Ka Shing Institute of Health Sciences The Chinese University of Hong Kong, Prince of Wales Hospital Hong Kong SAR China