1. Department of Obstetrics and Gynecology, Qingdao Municipal Hospital Group Qingdao University Qingdao Shandong China
2. Department of Anesthesiology, Qingdao Municipal Hospital Group Qingdao University Qingdao Shandong China
3. Department of Ultrasound, Qingdao Municipal Hospital Group Qingdao University Qingdao Shandong China
4. Department of Pathology, Qingdao Municipal Hospital Group Qingdao University Qingdao Shandong China
5. Department of Biochemistry and Molecular Biology, Basic Medical College Qingdao University Qingdao Shandong China