1. Department of General Surgery, Qingdao chengyang District People’s Hospital, Qingdao, Shandong, China
2. Department of Gynecology, Qingdao chengyang District People’s Hospital, Qingdao, Shandong, China
3. Department of Obstetrics, Qingdao chengyang District People’s Hospital, Qingdao, Shandong, China