1. Institute of Clinical Medicine, Faculty of Medicine University of Oslo Oslo Norway
2. Division of Paediatric and Adolescent Medicine Oslo University Hospital Oslo Norway
3. Division of Obstetrics and Gynaecology Oslo University Hospital Oslo Norway
4. Astrid Lindgren Children's Hospital Karolinska University Hospital Stockholm Sweden
5. Department of Women's and Children's Health Karolinska Institutet Stockholm Sweden
6. Oslo Centre of Biostatistics and Epidemiology Oslo University Hospital Oslo Norway
7. Faculty of Health VID Specialized University Oslo Norway
8. Department of Dermatology and Venereology Oslo University Hospital Oslo Norway