1. Center of Maternal-Fetal, Neonatal and Reproductive Medicine; National Center for Child Health and Development; Tokyo Japan
2. Department of Obstetrics and Gynecology; Showa University School of Medicine; Tokyo Japan
3. Department of Obstetrics and Gynecology; Hyogo College of Medicine; Nishinomiya Japan
4. Department of Obstetrics; Osaka City General Hospital; Osaka Japan
5. Department of Obstetrics and Gynecology; The Jikei University School of Medicine; Tokyo Japan
6. Department of Obstetrics and Gynecology; Nagoya City University Graduate School of Medical Sciences; Nagoya Japan
7. Department of Obstetrics and Gynecology; Aiiku Clinic; Tokyo Japan
8. Department of Obstetrics and Gynecology; Hokkaido University Graduate School of Medicine; Sapporo Japan
9. Department of Obstetrics and Gynecology; Tokyo Women's Medical University; Tokyo Japan
10. Department of Obstetrics and Gynecology; Toho University Omori Medical Center; Tokyo Japan
11. Department of Maternal and Fetal Medicine; Miyagi Children's Hospital; Sendai Japan
12. Department of Obstetrics; Osaka Medical Center and Research Institute for Maternal and Child Health; Osaka Japan
13. Department of Obstetrics and Gynecology; Saitama Medical University; Moroyama Japan
14. Department of Obstetrics and Gynecology; Yokohama City University Graduate School of Medicine; Yokohama Japan
15. Department of Obstetrics and Gynecology, Clinical Research Institute; National Kyusyu Medical Center; Fukuoka Japan
16. Department of Obstetrics and Gynecology; Nagasaki University School of Medicine; Nagasaki Japan
17. Department of Obstetrics and Gynecology; Tokai University School of Medicine; Isehara Japan