1. Department of Gynecology and Obstetrics; The First Affiliated Hospital of Xi'an Jiaotong University; Xi'an Shaanxi China
2. Department of Gynecology and Obstetrics; The Affiliated Hospital of Xi'an Medical College; Xi'an Shaanxi China
3. Department of Gynecology; The Affiliated Yan An Hospital of Kunming Medical University; Kunming Yunnan China