1. Department of Gynecology and Obstetrics Dalian Municipal Women and Children's Medical Center (Group) Dalian China
2. Department of Pathology Dalian Liaoyu Hospital Dalian China
3. Department of Gynecology and Obstetrics Dalian hospital of Shengjing Hospital Affiliated to China Medical University Dalian China
4. Department of Gynecology and Obstetrics Siping Maternal and Child Health Care Hospital Siping China