1. MOE‐Shanghai Key Laboratory of Children's Environmental Health Xinhua Hospital Shanghai Jiao Tong University School of Medicine Shanghai China
2. Department of Obstetrics and Gynecology Xinhua Hospital Shanghai Jiao Tong University School of Medicine Shanghai China
3. Department of Obstetrics The Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region Nanning China
4. Department of Obstetrics Shijiazhuang Obstetrics and Gynecology Hospital Hebei China
5. Department of Obstetrics and Gynecology Nanjing Drum Tower Hospital Nanjing University Medical School Jiangsu China
6. Department of Obstetrics The Maternal and Child Health Hospital of Dongchangfu District Shangdong China
7. Department of Obstetrics Shanghai First Maternity and Infant Hospital Tongji University School of Medicine Shanghai China
8. Department of Obstetrics The Maternal and Child Healthcare Hospital of Xiangtan Hunan China
9. Department of Obstetrics Qihetai Maternal and Child Health Hospital Heilongjiang China
10. Department of Obstetrics Fujian Provincial Maternity and Children's Hospital Fujian China
11. Department of Obstetrics and Gynecology Suzhou Municipal Hospital Nanjing University Medical School Jiangsu China
12. Department of Obstetrics and Gynecology Traditional Chinese Medicine Integrated Hospital of Tongzhou District Beijing China
13. Department of Obstetrics Northwest Women's and Children's Hospital Xi'an Jiao Tong University Shaanxi China
14. Department of Obstetrics Maternity and Child Care Center of Xingyang Henan China
15. Department of Obstetrics and Gynecology Wenzhou People's Hospital Wenzhou Maternal and Child Health Care Hospital The Third Clinical Institute Affiliated to Wenzhou Medical University Wenzhou Zhejiang China
16. Department of Obstetrics Inner Mongolia Maternity and Child Health Care Hospital Hohhot Inner Mongolia Autonomous Region China
17. Department of Obstetrics Changsha Hospital for Maternal and Child Health Care Hunan China
18. Department of Obstetrics and Gynecology The First Affiliated Hospital of Chongqing Medical University Chongqing China
19. Department of Obstetrics Haidian Maternal and Child Health Hospital Beijing China
20. Department of Obstetrics and Gynecology Renmin Hospital of Wuhan University Hubei China
21. Department of Obstetrics Beijing Obstetrics and Gynecology Hospital Capital Medical University Beijing China
22. Department of Obstetrics and Gynecology Jinhua People's Hospital Zhejiang China
23. Department of Obstetrics and Gynecology Wenling Maternal and Child Health Hospital Zhejiang China
24. Department of Obstetrics Shaoxing Maternal and Child Health Hospital Zhejiang China
25. Department of Obstetrics and Gynecology The Fifth Hospital of Xiamen Fujian China
26. Department of Obstetrics Gansu Provincial Maternity and Child‐care Hospital Lanzhou Gansu China
27. Department of Obstetrics Gaizhou Maternal and Child Health Hospital Liaoning China
28. Department of Obstetrics and Gynecology Jiangyin People's Hospital Southeast University School of Medicine Jiangsu China
29. Department of Obstetrics and Gynecology The First Hospital Affiliated to Army Medical University Chongqing China
30. UNDP/UNFPA/UNICEF/WHO/World Bank Special Programme of Research, Development and Research Training in Human Reproduction Department of Reproductive Health and Research World Health Organization (WHO) Geneva Switzerland