1. Perinatology Committee; Japan Society of Obstetrics & Gynecology
2. Department of Obstetrics and Gynecology; Juntendo University Faculty of Medicine; Tokyo
3. Department of Obstetrics and Gynecology; Hamamatsu Medical Center; Shizuoka
4. Department of Obstetrics and Gynecology; Aiwa Hospital; Saitama
5. Division of Obstetrics, Center of Maternal-Fetal, Neonatal and Reproductive Medicine; National Center for Child Health and Development; Tokyo
6. Department of Perinatology and Gynecology; Kagawa University Graduate School of Medicine; Kagawa
7. Department of Obstetrics and Gynecology; Nagasaki University Faculty of Medicine; Nagasaki Japan