1. Center for Clinical Epidemiology Odense University Hospital, University of Southern Denmark Odense Denmark
2. Research Unit of Clinical Epidemiology, Institute of Clinical Research University of Southern Denmark Odense Denmark
3. Department of Obstetrics and Gynecology Herlev Hospital Herlev Denmark
4. Department of Clinical Medicine University of Copenhagen Copenhagen Denmark
5. Department of Obstetrics and Gynecology Aalborg University Hospital Aalborg Denmark
6. Department of Clinical Medicine Aalborg University Aalborg Denmark