1. Departments of Pediatrics and Adolescent Medicine,
2. PEDEGO Research Unit and Medical Research Centre Oulu, University of Oulu, Oulu, Finland;
3. Health Care Centre, Oulu, Finland;
4. Department of Pediatrics, Institute of Clinical Medicine, University of Eastern Finland and Kuopio University Hospital, Kuopio, Finland; and
5. Obstetrics and Gynecology, and
6. Radiology, Oulu University Hospital, Oulu, Finland;
7. Biocenter Oulu, Oulu, Finland