1. Department of Obstetrics and Gynecology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, National Clinical Research Center for Obstetric & Gynecologic Diseases, Beijing, China
2. Department of Reproductive Medicine, The Second Hospital of Hebei Medical University, Hebei, China
3. Department of Obstetrics and Gynecology, The Affiliated Hospital of Qingdao University, Shandong, China
4. Department of Obstetrics and Gynecology, The Second Affiliated Hospital of Nanchang University, JiangXi, China
5. Department of Obstetrics and Gynecology, Hunan Provincial Maternal and Child Health Care Hospital, Hunan, China
6. Department of Obstetrics and Gynecology, Women and Children's Hospital of Jinzhou, Liaoning, China
7. Department of Obstetrics and Gynecology, Xinhui Maternity and Children's Hospital, Guangxi, China
8. Department of Gynecology, Guangzhou Women and Children’s Medical Centre, Guangdong, China
9. Department of Obstetrics and Gynecology, Zhongda Hospital Southeast Univeisity, Jiangsu, China
10. Department of Obstetrics and Gynecology, Liuzhou Maternity and Child Healthcare Hospital, GuangXi, China