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. West China University of Medical Sciences; 2001, 5, Clinical Department; Chinese EBM Center, WCUMS, No. 37, Guoxuexiang Street Chengdu Sichuan China 610041