1. Department of Obstetrics and Gynecology Hokkaido University Graduate School of Medicine Sapporo Japan
2. Department of Obstetrics and Gynecology Niigata University Graduate School of Medical and Dental Sciences Niigata Japan
3. Department of Obstetrics and Gynecology Akita University Graduate School of Medicine Akita Japan
4. Department of Obstetrics and Gynecology Kameda Medical Center Kamogawa Japan
5. Center for Maternal‐Fetal, Neonatal and Reproductive Medicine National Center for Child Health and Development Tokyo Japan
6. Department of Obstetrics and Gynecology Nara Medical University Kashihara Japan
7. Department of Obstetrics and Gynecology Nippon Medical School Tokyo Japan
8. Department of Gynecology and Obstetrics Kyoto University Graduate School of Medicine Kyoto Japan
9. Department of Gynecology and Obstetrics Kyoto University Hospital Kyoto Japan
10. Department of Obstetrics and Gynecology, Faculty of Life Sciences Kumamoto University Kumamoto Japan
11. Department of Obstetrics and Gynecology Shiga University of Medical Science Otsu Japan
12. Department of Obstetrics and Gynecology Japanese Red Cross Medical Center Tokyo Japan
13. Department of Obstetrics and Gynecology Yokohama City University School of Medicine Yokohama Japan
14. Department of Obstetrics and Gynecology Yodogawa Christian Hospital Osaka Japan
15. Departments of Obstetrics and Gynecology Osaka University Graduate School of Medicine Suita Japan
16. Department of Obstetrics and Gynecology Kitasato University School of Medicine Sagamihara Japan
17. Department of Obstetrics and Gynecology Tottori University School of Medicine Yonago Japan
18. Department of Reproductive Medicine Graduate School of Medicine, Chiba University Chiba Japan