1. Department of Pediatrics, Akita University Graduate School of Medicine, Akita, Japan
2. Department of Pediatrics, Saitama Medical Center, Saitama Medical University, Kawagoe, Japan
3. Department of Neonatology, Akita Red Cross Hospital, Akita, Japan
4. Department of Pediatrics and Child Health, Nihon University School of Medicine, Itabashi, Japan
5. Department of Pediatrics, University of Occupational and Environmental Health, Kitakyushu, Japan
6. Department of Public Health, Chiba University Graduate School of Medicine, Chiba, Japan