1. From the State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China (P.X., M.L., Hao Wang, Y.L., Haibin Wang, L.J., Y.W.); Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China (Y.Z., Y.W., J.Q.); Department of Obstetrics and Gynecology, Tangdu Hospital, the Fourth Military Medical University, Xi’an, China (X.Z., Y.Y.); and University of Chinese Academy of Sciences, Beijing, China (P.X., Hao Wang).