1. Department of Obstetrics and Gynecology Hirosaki University Graduate School of Medicine Hirosaki Aomori Japan
2. Department of Obstetrics and Gynecology Tokyo Women's Medical University Shinjuku Japan
3. Department of Obstetrics and Gynecology Showa University School of Medicine Tokyo Japan
4. Marunouchi no Mori Ladies Clinic Tokyo Japan
5. Women's Clinic We! Toyama Toyama Japan
6. Medical Corporation Women's Wellness Women's Life Clinic Tokyo Japan
7. Department of Obstetrics and Gynecology Juntendo University Urayasu Hospital Tokyo Japan
8. Aomori Women's Health Care Research Institute Hirosaki Aomori Japan
9. Department of Obstetrics and Gynecology Rinku General Medical Centre Osaka Japan
10. Center for Perinatal Medicine JCHO Sagamino Hospital Kanagawa Japan
11. Department of Obstetrics and Gynecology, Graduate School of Medical Sciences Kyushu University Fukuoka Japan
12. Department of Obstetrics and Gynecology Osaka University Graduate School of Medicine Osaka Japan