1. Department of Pediatrics Saitama Medical Center Saitama Medical University Kawagoe Saitama 350‐8550 Japan
2. Department of Neonatology Saitama Children's Medical Center Saitama Saitama 330‐8777 Japan
3. Department of Neonatology Hyogo Prefectural Kobe Children's Hospital Perinatal Center Kobe Hyogo 650‐0047 Japan
4. Department of Neonatology Tokyo Metropolitan Children's Medical Center Fuchu Tokyo 183‐8561 Japan
5. Department of Pediatrics Otsu Red Cross Hospital Otsu Shiga 520‐0046 Japan
6. Division of Neonatology Perinatal Center for Maternal and Child Health Saitama City Hospital Saitama Saitama 336‐8522 Japan
7. Department of Pediatrics Mie‐Chuo Medical Center Tsu Mie 514‐1101 Japan
8. Department of Neonatology Kanagawa Children's Medical Center Yokohama Kanagawa 232‐8555 Japan
9. Department of Pediatrics Takatsuki General Hospital Takatsuki Osaka 569‐1192 Japan
10. Department of Pediatrics Kobe University Graduate School of Medicine Kobe Hyogo 650‐0017 Japan
11. Division of Neonatology Okayama Medical Center National Hospital Organization Okayama Okayama 701‐1192 Japan