1. Department of Obstetrics and Gynecology Sørlandet Hospital Kristiansand Kristiansand Norway
2. Department of Life Science and Education University of South Wales Pontypridd UK
3. Department of Anesthesiology and Intensive Care Sørlandet Hospital Kristiansand Norway
4. Research Department Sørlandet Hospital Kristiansand Norway
5. Faculty of Health and Sport Science University of Agder Kristiansand Norway
6. Oslo Center for Biostatistics and Epidemiology Oslo University Hospital Oslo Norway
7. Department of Clinical Science University of Bergen Bergen Norway