1. West China Second University Hospital, Sichuan University; Department of Obstetrics and Gynecology; No. 17, Section Three, Ren Min Nan Lu Avenue Chengdu Sichuan China 610041
2. University of Iceland; Center of Public Health Sciences, Faculty of Medicine; Reykjavík Iceland
3. West China Second University Hospital, Sichuan University; Department of Orthopedics; No. 37, Guo Xue Xiang Chengdu Sichuan China 610041