1. Norwegian Research Centre for Women's Health Oslo University Hospital Oslo Norway
2. Department of Obstetrics Drammen Hospital Drammen Norway
3. Department of Obstetrics Rigshospitalet University Hospital Copenhagen Denmark
4. Institution for Women's and Children's Health Department for Obstetrics and Gynecology Uppsala University Uppsala Sweden
5. Information Services Department THL Finnish Institute for Health and Welfare Helsinki Finland
6. Department of Neurobiology, Care Sciences and Society Karolinska Institute Stockholm Sweden
7. Nordsjællands Hospital Hillerød Denmark
8. Department of Women's and Children's Health Karolinska InstituteKarolinska University Hospital Stockholm Sweden
9. Department of Obstetrics Oslo University Hospital Rikshospitalet Oslo Norway
10. Institute of Clinical Medicine University of Oslo Oslo Norway