1. Department of the Japan Obstetric Compensation System for Cerebral Palsy in Public Interest Incorporated Foundation Japan Council for Quality Health Care Tokyo Japan
2. Department of Obstetrics and Gynecology Showa University Northern Yokohama Hospital Yokohama Japan
3. Department of Public Health, Graduate School of Medicine University of Tokyo Tokyo Japan
4. Department of Obstetrics and Gynecology, Faculty of Medicine Miyazaki University Miyazaki Japan
5. Department of Obstetrics Oita Prefectural Hospital Oita Japan
6. Department of Obstetrics and Gynecology Saint Marianna University School of Medicine Kawasaki Japan
7. Department of Obstetrics and Gynecology Mie University Tsu Japan
8. Department of Health Services Research, Faculty of Medicine Tsukuba University Tsukuba Japan
9. Department of Obstetrics and Gynecology Nippon Medical University Tokyo Japan
10. Department of Obstetrics and Gynecology Fukushima Medical University Fukushima Japan
11. Maeda Obstetrics and Gynecology Clinic Yaizu Japan
12. Department of Obstetrics and Gynecology Hamamatsu University School of Medicine Hamamatsu Japan
13. Department of Obstetrics and Gynecology Nagasaki University Nagasaki Japan
14. Kugayama Hospital Tokyo Japan
15. Department of Obstetrics and Gynecology Juntendo University Tokyo Japan