Peking University - Department of Obstetrics and Gynecology, Peking University - Department of Obstetrics and Gynecology, Jiangxi Maternal and Child Health Hospital - Department of Obstetrics and Gynecology, Maternal and Children Health Hospital of Guangxi Zhuang Autonomous Region - Department of Obstetrics and Gynecology, Guizhou Provincial People's Hospital - Department of Obstetrics and Gynecology, Kunming City Maternal and Child Health Hospital, XinJiang Changji Maternal and Child Health and Family Planning Service Center - Department of Women’s Health Care, Xining First People's Hospital, Zhejiang University - Department of Obstetrics and Gynecology, Jilin University (JLU) - Department of Obstetrics and Gynecology, China Medical University - Department of Obstetrics and Gynecology, Xi'an Jiaotong University (XJTU) - Department of Obstetrics and Gynecology, Maternal and Child Health and Family Planning Service Center of Zhengxiangbaiqi - Department of Obstetrics and Gynecology, Peking University - Department of Obstetrics and Gynecology, Peking University - Department of Obstetrics and Gynecology, Peking University - Department of Obstetrics and Gynecology, Peking University - Department of Obstetrics and Gynecology, Peking University - Department of Obstetrics and Gynecology and Peking University - Department of Obstetrics and Gynecology