1. Department of Paediatrics; St. Luke's International Hospital; Tokyo Japan
2. Centre of Clinical Epidemiology; St. Luke's Life Science Institute; Tokyo Japan
3. Department of Paediatrics; Nippon Medical School; Tokyo Japan
4. School of Public Health; University of California; Berkeley CA USA
5. Division of Oncology; National Centre for Child Health and Development; Tokyo Japan
6. Department of Paediatrics and Developmental Biology; Tokyo Medical and Dental University; Tokyo Japan
7. Department of Paediatrics; Jikei University School of Medicine; Tokyo Japan
8. Department of Paediatrics; Yokohama City University School of Medicine; Yokohama Japan
9. Department of Paediatrics and Adolescent Medicine; Juntendo University School of Medicine; Tokyo Japan
10. Department of Paediatrics; Dokkyo Medical University; Tochigi Japan
11. Department of Paediatrics; Yachimata Hospital; Chiba Japan
12. Department of General Paediatrics; National Centre for Child Health and Development; Tokyo Japan
13. Department of Paediatrics; Nagano Prefectural Suzaka Hospital; Nagano Japan
14. Department of Paediatrics; Ibaraki Children's Hospital; Mito Japan
15. First Department of Paediatrics; Toho University; Tokyo Japan