1. School of Public Health, Health Science Center, Xi’an Jiaotong University, 76 West Yanta Road, Xi’an 710061, China
2. Department of Infection Control, The First Affiliated Hospital of Xiamen University, 55 Zhenhai Road, Xiamen, 361003, China
3. Department of Gynecology and Obstetrics, The First Affiliated Hospital of Xiamen University, 55 Zhenhai Road, Xiamen, 361003, China