1. Department of Obstetrics and Gynecology, Shanghai First Maternity and Infant Health Hospital, Tongji University School of Medicine, Shanghai, China
2. Department of Obstetrics and Gynecology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
3. Department of Obstetrics and Gynecology, The First Affiliated Hospital of Soochow University, Suzhou, China