1. Department of Obstetrics and Gynecology Hokkaido University Graduate School of Medicine Sapporo Japan
2. Department of Obstetrics and Gynecology Yokohama City University Hospital Yokohama Japan
3. Department of Public Health Dokkyo Medical University, School of Medicine Tochigi Japan
4. Department of Obstetrics and Gynecology University of Toyama Toyama Japan
5. Division of Microbiology, Department of Pathology and Microbiology Nihon University School of Medicine Tokyo Japan
6. Department of Obstetrics and Gynecology Nihon University School of Medicine Tokyo Japan
7. Department of Obstetrics and Gynecology Keio University School of Medicine Tokyo Japan
8. Department of Pediatrics and Child Health Nihon University School of Medicine Tokyo Japan
9. Department of Obstetrics and Gynecology Kobe University Graduate School of Medicine Kobe Japan