1. Department of Obstetrics and Gynecology; Sahlgrenska Academy at Gothenburg University; Sahlgrenska University Hospital; Gothenburg Sweden
2. Research Group Epidemiology of Chronic Diseases; Department of Community Medicine; Faculty of Health Sciences; UiT The Arctic University of Norway; Tromsø Norway
3. Department of Women's and Children's Health; Division of Obstetrics and Gynecology; Karolinska Institutet; Karolinska University Hospital; Stockholm Sweden
4. Department of Obstetrics and Gynecology; University of Helsinki and Helsinki University Hospital; Helsinki Finland
5. Department of Obstetrics & Gynecology; Faculty of Health Sciences; Rigshospitalet University Hospital; University of Copenhagen; Copenhagen Denmark