Department of Obstetrics and Gynecology Peking Union Medical College Hospital Peking Union Medical College Chinese Academy of Medical Sciences Beijing 100730 China;
Department of Obstetrics and Gynecology West China Second Hospital Sichuan University Key Laboratory of Birth Defects and Related Diseases of Women and Children Ministry of Education Chengdu Sichuan 061110 China;
Department of Obstetrics and Gynecology Peking University People's Hospital Beijing 100044 China;
Department of Obstetrics and Gynecology Peking University People's Hospital Beijing 100044 China;
Department of Obstetrics and Gynecology The Second Hospital of Hebei Medical University Shijiazhuang Hebei 075100 China;
Department of Obstetrics and Gynecology Qilu Hospital of Shandong University Jinan Shandong 250002 China;
Department of Obstetrics and Gynecology 900 Hospital of the Joint Logistics Team Fuzhou Fujian 350025 China;
Department of Obstetrics and Gynecology Women's Hospital School of Medicine Zhejiang University Hangzhou Zhejiang 310000 China;
Department of Obstetrics and Gynecology Nanjing First Hospital Nanjing Medical University Nanjing Jiangsu 210006 China;
Department of Obstetrics and Gynecology The Third Affiliated Hospital of Zhengzhou University Zhengzhou Henan 450000 China;
Department of Obstetrics and Gynecology Shanghai Jiao Tong University Sixth Hospital Shanghai 200300 China;
Department of Obstetrics and Gynecology Graduate School of Peking Union Medical College Chinese Academy of Medical Sciences Beijing 100730 China;
Department of Gynecology The Affiliated Wuxi Maternity and Child Health Care Hospital of Nanjing Medical University Wuxi Jiangsu 214002 China;
Department of Obstetrics and Gynecology The Affiliated Yantai Yuhuangding Hospital of Qingdao University Yantai Shandong 264000 China;
Department of Gynecology Jiangxi Maternal and Child Health Hospital Nanchang Jiangxi 330006 China;
Department of Gynecology Shanxi Maternal and Child Health Hospital Taiyuan Shanxi 030013 China;
Department of Obstetrics and Gynecology The First Affiliated Hospital of Army Medical University(Southwest Hospital) Chongqing 400038 China;
Department of Obstetrics and Gynecology Shengjing Hospital of China Medical University Shenyang Liaoning 110004 China;
Department of Gynecology The First Affiliated Hospital of Xinjiang Medical University Urumqi Xinjiang 831118 China;
Department of Gynecology Gansu Province Maternity and Child-care Hospital Lanzhou Gansu 730050 China;
Department of Obstetrics and Gynecology Peking Union Medical College Hospital Peking Union Medical College Chinese Academy of Medical Sciences Beijing 100730 China;
Department of Obstetrics and Gynecology Peking Union Medical College Hospital Peking Union Medical College Chinese Academy of Medical Sciences Beijing 100730 China;
Department of Epidemiology and Biostatistics Institute of Basic Medical Sciences Chinese Academy of Medical Sciences and School of Basic Medicine Peking Union Medical College Beijing 100730 China;
Department of Obstetrics and Gynecology The Fourth Medical Center Chinese PLA General Hospital Beijing 100048 China;
Department of Gynecology Obstetrics and Gynecology Hospital of Fudan University Shanghai 200433 China;
Department of Obstetrics and Gynecology Peking University Third Hospital Beijing 100083 China;
Department of Obstetrics and Gynecology Tongji Hospital Tongji University Shanghai 200065 China;
Department of Obstetrics and Gynecology Tongji Hospital Tongji University Shanghai 200065 China;
