Institution: | 1.Department of Obstetrics and Gynecology, The Third Central Clinical College of Tianjin Medical University, Tianjin 300170, China;2.Department of Obstetrics and Gynecology, Characteristic Medical Center of Chinese People''s Armed Police Force, Tianjin 300170, China;3.Department of Obstetrics and Gynecology, Tianjin Third Central Hospital, Tianjin 300170, China;4.Department of Obstetrics and Gynecology, Tianjin Medical University General Hospital, Tianjin 300170, China |