1. Department of Obstetrics and Gynecology, School of Medicine, Ren Ji Hospital, Shanghai Jiao Tong University, Shanghai, China;
2. Department of Obstetrics and Gynecology, Tongji Hosptial, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China;
3. Department of Gynecology and Obstetrics, Xiangya Hospital, Central South University, Changsha, China;
4. Department of Obstetrics and Gynecology, West China Second University Hospital, Sichuan University, Chengdu, China