1. Department of Obstetrics and Gynecology, China-Japan Friendship Hospital, Beijing, China
2. Department of Obstetrics and Gynecology, Anhui Provincial Hospital Affiliated to Anhui Medical University, Hefei, China
3. Department of Gynecology and Oncology, Anhui Provincial Cancer Hospital, Hefei, China
4. School of Medicine, Tsinghua University, Beijing, China