1. Department of Vascular Surgery, Qingdao Municipal Hospital, Qingdao 266000, China
2. Department of Obstetrics, Qingdao Municipal Hospital, Qingdao 266000, China
3. Department of Obstetrics and Gynecology, The First Hospital of Jilin University, Jilin University, No.71 Xinmin Street, Changchun, Jilin Province 130021, China