1. Department of Obstetrics and Gynecology, The Third Hospital of Hebei Medical University, Shijiazhuang, Hebei 050000, P.R. China
2. Department of Oncology, Hebei General Hospital, Shijiazhuang, Hebei 050000, P.R. China
3. Teaching and Research Section of Obstetrics and Gynecology, Hebei Medical University, Shijiazhuang, Hebei 050000, P.R. China