1. Department of Obstetrics and Gynecology Niigata University Graduate School of Medical and Dental Sciences Niigata Japan
2. Hokkaido University Center for Environmental and Health Sciences Sapporo Japan
3. Department of Preventive Medicine Faculty of Medicine Saga University Saga Japan
4. Departments of Obstetrics and Gynecology Osaka University Graduate School of Medicine Osaka Japan
5. Department of Obstetrics and Gynecology Yokohama City University School of Medicine Yokohama Japan
6. Center for Cancer Control and Information Services National Cancer Center Tokyo Japan