1. University of Helsinki; Helsinki Finland
2. Department of Obstetrics and Gynecology; Helsinki University Hospital; Helsinki Finland
3. National Institute for Health and Welfare THL; Helsinki Finland
4. Department of Neurobiology; Care Sciences and Society; Division of Family Medicine; Karolinska Institute; Stockholm Sweden
5. University of Copenhagen; Copenhagen Denmark
6. Department of Obstetrics and Gynecology; Nordsjaelland Hospital; Hillerod Denmark
7. Department of Obstetrics; Rigshospitalet; Copenhagen Denmark
8. The Icelandic Birth Registry; Akureyri Iceland
9. Institute of Health Science Research; University of Akureyri; Akureyri Iceland
10. Landspitali University Hospital; Reykajvik Iceland
11. Swedish National Board of Health and Welfare; Stockholm Sweden
12. University of Lund; Lund Sweden
13. Department of Health Registries; Norwegian Institute of Public Health; Bergen Norway
14. Department of Clinical Science; University of Bergen; Bergen Norway
15. Haukeland University Hospital; Bergen Norway
16. Department of Community Medicine; Faculty of Health Sciences; UiT the Arctic University of Norway; Tromsø Norway
17. Hyvinkää Hospital; Hyvinkää Finland