1. Medical Record Management Section, Weifang People's Hospital, Weifang, Shandong 261041, P.R. China
2. Department of Obstetrics and Gynecology, Qingdao Hospital of Traditional Chinese Medicine, Qingdao Hiser Hospital, Qingdao, Shandong 266033, P.R. China
3. Department of Obstetrics and Gynecology, Jiyang People's Hospital, Jinan, Shandong 251400, P.R. China
4. Department of Cardiothoracic Surgery, The People's Hospital of Zhangqiu Area, Jinan, Shandong 250200, P.R. China
5. Department of Radiology, The People's Hospital of Zhangqiu Area, Jinan, Shandong 250200, P.R. China
6. Department of Health Management, Weifang People's Hospital, Weifang, Shandong 261041, P.R. China