1. Department of Gynecology and Obstetrics Keio University School of Medicine Tokyo Japan
2. Department of Obstetrics and Gynecology Tottori University School of Medicine Tottori Yonago Japan
3. Department of Obstetrics and Gynecology Nihon University School of Medicine Tokyo Japan
4. Department of Obstetrics and Gynecology The Jikei University School of Medicine Tokyo Japan
5. Department of Obstetrics and Gynecology Tokai University Kanagawa Hiratsuka Kanagawa Japan
6. Department of Obstetrics and Gynecology, Faculty of Life Sciences Kumamoto University Kumamoto Japan