1. Department of Reproductive Medicine, Binzhou Medical University Hospital, Binzhou City, Shandong Province, China
2. Department of Colorectal and Hernial Surgery, Binzhou Medical University Hospital, Binzhou City, Shandong Province, China
3. Department of Obstetrics and Gynecology, Binzhou Central Hospital, Binzhou City, Shandong Province, China
4. Department of Obstetrics and Gynecology, The Third Affiliated Hospital of Chongqing Medical University, Chongqing, China