1. West China Second University Hospital, Sichuan University; Department of Obstetrics and Gynecology; No. 17, Section Three, Ren Min Nan Lu Avenue Chengdu Sichuan China 610041
2. West China Second University Hospital, West China Women's and Children's Hospital; Department of Obstetrics and Gynecology; No. 17, Section Three, Ren Min Nan Lu Avenue Chengdu Sichuan China 610041
3. The Second Affiliated Hospital of Chongqing Medical University; The Obstetrics and Gynecology Department; 76 Linjiang Rd Chongqing China 400010