1. Department of Maternal Fetal Medicine; Osaka Medical Center and Research Institute for Maternal and Child Health; Izumi Japan
2. Center of Maternal-Fetal, Neonatal and Reproductive Medicine; National Center for Child Health and Development; Tokyo Japan
3. Department of Medical Statistics; Faculty of Medicine, Toho University; Yokohama Japan
4. Department of Obstetrics; Hyogo Prefectural Kobe Children's Hospital; Kobe Japan
5. Maternal and Perinatal Care Center; Seirei Hamamatsu General Hospital; Hamamatsu Japan
6. Department of Obstetrics and Gynecology; Jikei University School of Medicine; Tokyo Japan
7. Department of Obstetrics; Kanagawa Children's Medical Center; Yokohama Japan
8. Department of Obstetrics and Gynecology; Showa University; Tokyo Japan
9. Department of Obstetrics and Gynecology; Kyorin University; Tokyo Japan
10. Department of Obstetrics; Miyagi Children's Hospital; Sendai Japan