1. Department of Gynecology and Obstetrics, Children’s Hospital of Shanxi and Women Health Center of Shanxi , Taiyuan , China
2. Department of Laboratory Medicine, Shanxi Provincial People’s Hospital , Taiyuan , China
3. Department of Pathology, Stanford University School of Medicine , Stanford , CA 94305 , United States of America
4. Department of Gynecology and Obstetrics, Coal Hospital of Shanxi , Taiyuan , China