1. Medical School of Chinese PLA, Department of Obstetrics and Gynecology The First Medical Center, Chinese PLA General Hospital, Beijing, China
2. Department of Obstetrics and Gynecology, The First Medical Center of Chinese PLA General Hospital, Beijing, China
3. Blood Transfusion Department, The First Medical Center of Chinese PLA General Hospital, Beijing, China
4. The Eighth Medical Center of Chinese PLA General Hospital, Beijing, China
5. Anzhen Hospital Affiliated to Capital Medical University, Beijing, China