1. Department of Pediatrics, Showa University School of Medicine, Tokyo, Japan
2. Department of Pediatrics, St Marianna University School of Medicine, Kawasaki, Japan
3. Department of Neonatology, Maternal and Perinatal Center, Tokyo Women's Medical University, Tokyo, Japan
4. Department of Neonatology, Maternal and Child Health Center, Aiiku Hospital, Tokyo, Japan
5. Department of Neonatology, Kanagawa Children's Medical Center, Yokohama, Japan
6. Department of Human Welfare, Faculty of Human Science, Taisyo University, Tokyo, Japan
7. Department of Neonatology, Osaka Medical Center and Research Institute for Maternal and Child Health, Osaka, Japan
8. Department of Pediatrics, Kobe University School of Medicine, Kobe, Japan