1. Department of Obstetrics and Gynecology, People’s Hospital of Linyi Economic Development Area, Linyi, Shandong, China
2. Department of Gynecology, The Affiliated Qingdao Hiser Hospital of Qingdao University, Qingdao, Shandong, China
3. Department of Obstetrics and Gynecology, Hedong People’s Hospital, Linyi, Shandong, China