1. Department of Gynecology, Women and Children's Hospital, Qingdao University, Qingdao, Shandong 266000, P.R. China
2. Department of Pediatrics, Eighth People's Hospital of Qingdao Shandong, Qingdao University, Qingdao, Shandong 266000, P.R. China
3. Department of Imaging, Women and Children's Hospital, Qingdao University, Qingdao, Shandong 266000, P.R. China
4. Department of General Internal Medicine, Women and Children's Hospital, Qingdao University, Qingdao, Shandong 266000, P.R. China