1. Department of Obstetrics and Gynecology Keio University School of Medicine Tokyo Japan
2. Department of Obstetrics and Gynecology National Hospital Organization Saitama Hospital Saitama Japan
3. Department of Obstetrics and Gynecology School of Medicine Fujita Health University Aichi Japan
4. Department of Obstetrics and Gynecology International University of Health and Welfare School of Medicine Chiba Japan