Liu Jiashu, Fan Bo△, Huang Jin, Liu Shengfeng <br>(Department of Obstetrics and Gynecology, Affiliated Hospital of North Sichuan Medical College, Nanchong, Sichuan 637000)
Liu Jiashu, Fan Bo △, Huang Jin, Liu Shengfeng<br>(Obstetrics and Gynecology, Affiliated Hospital of North Sichuan Medical College, Nanchong, Sichuan 637000)<br>