1. Department of Gynecology and Obstetrics, First Affiliated Hospital of Dalian Medical University, Dalian, Liaoning, China;
2. Institute of High Altitude Medicine, Department of Gynecology and Obstetrics, People’s Hospital of Naqu, Naqu, Tibet, China;
3. Department of Pathology, Dalian Obstetrics and Gynecology Hospital, Dalian, Liaoning, China;
4. Department of Pathology, First Affiliated Hospital of Dalian Medical University, Dalian, Liaoning, China;
5. International Education College of Dalian Medical University, Dalian, Liaoning, China