1. Department of Public Health, Research Unit of Epidemiology, Aarhus University , Aarhus C, Denmark
2. Department of Public Health, Research Unit for General Practice, Aarhus University , Aarhus C, Denmark
3. Department of Obstetrics and Gynecology, Aalborg University Hospital , Aalborg, Denmark
4. DEFACTUM, Central Denmark Region , Aarhus N, Denmark
5. Department of Clinical Medicine, Danish Centre for Health Services Research, Aalborg University , Gistrup, Denmark
6. Department of Obstetrics and Gynecology, Aarhus University Hospital , Aarhus N, Denmark
7. Nuffield Department of Women’s and Reproductive Health, John Radcliffe Hospital, Oxford University , Oxford, UK