Chinese Academy of Medical Sciences - Department of Obstetrics and Gynecology, Chinese Academy of Medical Sciences - Department of Obstetrics and Gynecology, Southern Medical University - Department of Gynaecology and Obstetrics, Chinese Academy of Medical Sciences - Department of Obstetrics and Gynecology, Chinese Academy of Medical Sciences - Department of Obstetrics and Gynecology, Chinese Academy of Medical Sciences - Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences - Department of Epidemiology and Statistics, Children’s Hospital of Shanxi Province, Maternal and Child Health Hospital of Wuxi, Maternal and Child Health Hospital of Gansu Province, Maternal and Child Health Hospital of Foshan, Guiyang Maternal and Child Health Care Hospital, China Medical University - Department of Obstetrics and Gynecology and Chinese Academy of Medical Sciences & Peking Union Medical College (CAMS & PUMC) - Department of Obstetrics and Gynecology