1. Department of Gynecology, Xiangya Hospital, Central South University, Changsha, Hunan, China
2. Department of Gynecology, The First Affiliated Hospital of Hunan University of Medicine, Huaihua, Hunan, China
3. Department of Gynecology, Xiangdong Hospital Affiliated to Hunan Normal University, Liling, Hunan, China
4. Department of Gynecology, Xiangya Changde Hospital, Changde, Hunan, China