1. Tianjin Women and Children's Health Centre; Tianjin China
2. Department of Epidemiology and Biostatistics; School of Public Health; Tianjin Medical University; Tianjin China
3. Department of Medicine and Therapeutics; Hong Kong Institute of Diabetes and Obesity and Li Ka Shing Institute of Health Science; Chinese University of Hong Kong; Prince of Wales Hospital; Hong Kong SAR China
4. Chronic Disease Epidemiology Laboratory; Pennington Biomedical Research Center; Baton Rouge LA USA
5. Population Cancer Research Program and Department of Pediatrics; Dalhousie University; Halifax Canada