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. Royal United Hospital; Cochrane Gynaecological, Neuro-oncology and Orphan Cancer Group; Education Centre Bath UK BA1 3NG
3. West China Second University Hospital, Sichuan University; Department of Obstetrics and Gynaecology; 20, 3rd Section, Ren Min Nan Rd Chengdu Sichuan China 610041
4. Karolinska Institutet; Department of Medical Epidemiology and Biostatistics; Box 281 Stockholm Sweden SE-17177
5. West China Hospital, Sichuan University; Department of Orthopedics; No. 37, Guo Xue Xiang Chengdu Sichuan China 610041