1. Department of Gynecology and Obstetrics, The First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi Province, China
2. Department of Gynecology and Obstetrics, Xi’an North Hospital, Xi’an, Shaanxi Province, China
3. Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi Province, China