1. Department of Obstetrics and Gynecology, Daqing Oilfield General Hospital, Daqing, P.R. China
2. Department of Oncology, Daqing Oilfield General Hospital and Huiren Cancer Hospital, Daqing, P.R. China
3. Department of Oncology, the 962 Hospital, Joint Logistics Support of the Chinese People’s Liberation Army, Harbin, P.R. China
4. Department of Obstetrics and Gynecology, the 962 Hospital, Joint Logistics Support of the Chinese People’s Liberation Army, Harbin, P.R. China