1. Center for Reproductive Medicine Department of Obstetrics and Gynecology Peking University Third Hospital Beijing China
2. National Clinical Research Center for Obstetrics and Gynecology, Peking University Third Hospital Beijing China
3. Key Laboratory of Assisted Reproduction, Peking University Ministry of Education Beijing China
4. Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproductive Technology Beijing China
5. Department of Obstetrics and Gynecology Beijing Jishuitan Hospital, Fourth Clinical College of Peking University Beijing China
6. Department of Obstetrics and Gynecology Peking University Third Hospital Beijing China
7. National Center for Healthcare Quality Management in Obstetrics Beijing China