1. Departments of Clinical Science, Paediatrics, Umeå University, Sweden
2. Public Health and Clinical Medicine, Epidemiology, Umeå University, Sweden
3. Departments of Paediatrics, Göteborg University, Sweden
4. Lund University, Sweden
5. Danderyd Hospital, Sweden
6. Uppsala University, Sweden
7. Örebro Medical Centre, Sweden
8. Norrköping Hospital, Sweden