1. Centre for Fertility and Health, Norwegian Institute of Public Health, 0213 Oslo, Norway
2. MRC Integrative Epidemiology Unit, University of Bristol, Bristol, UK
3. Bristol Medical School, Population Health Sciences, Bristol, UK
4. Epidemiology Branch, National Institute of Environmental Health Sciences, NC, USA
5. Institute of Military Medicine and Epidemiology, Norwegian Armed Forces Joint Medical Services, Sessvollmoen, Norway
6. Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway
7. Department of Public Health and Nursing, Norwegian University of Science and Technology, Trondheim, Norway
8. Department of Health Registries, Norwegian Institute of Public Health, Norway
9. Department of Clinical Science, University of Bergen, Bergen, Norway
10. Department of Paediatrics, Haukeland University Hospital, Bergen, Norway