Qian Wang1, Xiaomeng Ma2,3, Xiaosong Zhang4, Jason J Ong5, Jun Jing3, Lei Zhang6,7,8,9, Lin-Hong Wang10,11. 1. National Center for Women and Children's Health, China Center for Disease Control, Beijing, China. 2. Division of Health Sciences Informatics, Johns Hopkins School of Medicine, Baltimore, Maryland, USA. 3. Research Center for Public Health School of Medicine, Tsinghua University, Beijing, China. 4. Department of Obstetrics and Gynecology, Peking University First Hospital, Beijing, China. 5. Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK. 6. Department of Epidemiology and Biostatistics, School of Public Health, Xi'an Jiaotong University, Xi'an, Shaanxi, China linhong@chinawch.org.cn lei.zhang1@monash.edu. 7. School of Public Health and Preventive Medicine Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, Victoria, Australia. 8. Melbourne Sexual Health Centre, Alfred Health, Melbourne, Victoria, Australia. 9. Nursing and Health Sciences Faculty of Medicine, Monash University Central Clinical School, Melbourne, Victoria, Australia. 10. National Center for Chronic and Non-communicable Disease Control and Prevention, China Center for Disease Control, Beijing, China linhong@chinawch.org.cn lei.zhang1@monash.edu. 11. Branch of Women Health, Chinese Preventive Medicine Association, Beijing, China.