1. Department of Clinical and Molecular Medicine Norwegian University of Science and Technology Trondheim Norway
2. Department of Obstetrics and Gynecology St. Olav's Hospital University Hospital of Trondheim Trondheim Norway
3. Department of Gynecology Oslo University Hospital Oslo Norway
4. Institute of Clinical Medicine University of Oslo Oslo Norway
5. Norwegian System of Patient Injury Compensation Oslo Norway
6. Department of Surgery Akershus University Hospital Lørenskog Norway