1. Department of Obstetrics and Gynecology, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China (mainland)
2. Department of Obstetrics and Gynecology, Beijing Huai-Rou Hospital, Beijing, China (mainland)
3. Department of Pathology, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China (mainland)
4. Department of Radiology, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China (mainland)