1. Tampere School of Public Health, University of Tampere, Finland
2. Department of Pediatrics, University of Oulu, Finland
3. Department of Pediatrics, Tampere University Hospital, Tampere, and Hospital for Children and Adolescents, Helsinki University Hospital, Helsinki, Finland
4. Unit of Nutrition, Dept.of Epidemiology and Health Promotion, National Institute of Public Health, Helsinki, Tampere School of Public Health, Medical Research Found of Tampere, Dept.of Pediatrics, Tampere University Hospital, Tampere, Finland