1. Department of Obstetrics and Gynecology, Keio University School of Medicine, Tokyo, Japan.
2. Department of Preventive Medicine and Public Health, Keio University School of Medicine, Tokyo, Japan.
3. Department of Obstetrics and Gynecology, International University of Health and Welfare, Narita, Japan.
4. Department of Obstetrics and Gynecology, Hirosaki University Graduate School of Medicine, Hirosaki, Japan.
5. Department of Gynecologic Oncology, National Hospital Organization Shikoku Cancer Center, Matsuyama, Japan.
6. Department of Obstetrics and Gynecology, Kyoto University Graduate School of Medicine, Kyoto, Japan.
7. Department of Obstetrics and Gynecology, The Jikei University School of Medicine, Tokyo, Japan.