1. Department of Obstetrics and Gynecology, Sichuan Academy of Medical Sciences, Sichuan Provincial People’s Hospital, Chengdu, China;
2. Department of Obstetrics and Gynecology, the First Affiliated Hospital of Chongqing Medical University, Chongqing, China;
3. China-Canada-New Zealand Joint laboratory of Maternal and Fetal Medicine, Chongqing Medical University, Chongqing, China