1. Peking Union Medical College Graduate School, Beijing 100000, China
2. National Research Institute for Health and Family Planning, Beijing 100000, China
3. Reproductive Medicine Center of Henan Provincial People's Hospital, Zhengzhou 450003, China
4. Center for Reproductive Medicine, Peking University Third Hospital, Beijing 100191, China
5. National Clinical Research Center for Obstetrics and Gynecology, Beijing 100191, China
6. Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto M5S3M2, Canada