1. Department of Obstetrics and Gynecology, Tohoku University School of Medicine
2. Department of Obstetrics and Gynecology, National Hospital Organization Sendai Medical Center
3. Tohoku Medical Megabank Organization, Tohoku University
4. Division of Public Health, Hygiene and Epidemiology, Tohoku Medical and Pharmaceutical University Faculty of Medicine
5. Department of Gynecology, Miyagi Cancer Center