1 Institute of Medical Innovation and Research, Third Hospital, Health Science Center, Peking University, Beijing 100086, China; National Clinical Research Center for Obstetrics and Gynecology, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China; Key Laboratory of Assisted Reproduction (Peking University), Ministry of Education, Beijing, China; Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproductive Technology, Beijing, China. Electronic address: jie.qiao@263.net.
2 Institute of Medical Innovation and Research, Third Hospital, Health Science Center, Peking University, Beijing 100086, China; National Clinical Research Center for Obstetrics and Gynecology, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China; Key Laboratory of Assisted Reproduction (Peking University), Ministry of Education, Beijing, China; Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproductive Technology, Beijing, China.