1. Department of Obstetrics and Gynecology Tottori University Tottori Japan
2. Department of Gynecology and Obstetrics Osaka University School of Medicine Osaka Japan
3. Department of Gynecology and Obstetrics Keio University School of Medicine Tokyo Japan
4. Center for Recurrent Pregnancy Loss Teine Keijinkai Hospital Sapporo Japan
5. Department of Obstetrics Miyagi Children's Hospital Miyagi Japan
6. Department of Obstetrics and Gynecology University of Occupational and Environmental Health Fukuoka Japan
7. Department of Obstetrics and Gynecology Nihon University School of Medicine Tokyo Japan
8. Department of Obstetrics and Gynecology School of Medicine Hyogo Medical University Nishinomiya Japan