1. Department of Obstetrics and Gynecology, Faculty of Medicine; University of Tsukuba; Ibaraki Japan
2. Department of Obstetrics and Gynecology; Tokyo Dental College Ichikawa General Hospital; Chiba Japan
3. Department of Gynecologic Oncology; Cancer Institute Hospital of Japanese Foundation for Cancer Research; Tokyo Japan
4. Department of Obstetrics and Gynecology; Nara Medical University; Nara, Japan
5. Department of Obstetrics and Gynecology; Keio University School of Medicine; Tokyo Japan
6. Department of Obstetrics and Gynecology; St. Marianna University School of Medicine; Kanagawa Japan