1 Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway; Department of Obstetrics and Gynecology, Haukeland University Hospital, Bergen, Norway. Electronic address: hilde.engjom@uib.no.
2 Departments of Global Public Health and Primary Care, and Clinical Medicine, University of Bergen, Bergen, Norway; Department of Obstetrics and Gynecology, Haukeland University Hospital, Bergen, Norway.
3 Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway; Department of Obstetrics and Gynecology, Haukeland University Hospital, Medical Birth Registry of Norway, Norwegian Institute for Public Health, Bergen, Norway.