1. Department of Obstetrics and Gynecology, Peking University People’s Hospital, Beijing, China;
2. Department of Obstetrics and Gynecology, The Second Hospital of Hebei Medical University, Shijiazhuang, Hebei Province, China;
3. Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China;
4. Beijing Key Laboratory of Hematopoietic Stem Cell Transplantation, Peking University Institute of Hematology, People’s Hospital, Beijing, China