1. Department of Gynecology and Obstetrics, Yangpu Hospital, Tongji University School of Medicine, Shanghai 200090, P.R. China
2. Department of Gynecology and Obstetrics, Shanghai Pudong Hospital, Fudan University School of Medicine, Shanghai 510070, P.R. China
3. Department of Gynecology and Obstetrics, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai 200072, P.R. China