1. Department of Medical Epidemiology and Biostatistics Karolinska Institutet Solna Sweden
2. Department of Pediatrics Örebro University Hospital Örebro Sweden
3. Centre for Fertility and Health Norwegian Institute of Health Oslo Norway
4. Department of Global Public Health and Primary Care University of Bergen Bergen Norway
5. Department of Health Registry Research and Development Norwegian Institute of Health Bergen Norway
6. Department of Clinical Science University of Bergen Bergen Norway
7. Department of Public Health University of Copenhagen Copenhagen Denmark
8. Department of Medicine Karolinska Institutet Solna Sweden
9. Department of Women's Health and Division of Obstetrics Karolinska University Hospital Stockholm Sweden