1. Department of Surgery, Danderyd Hospital & Department of Clinical Sciences Danderyd Hospital, Karolinska Institutet Stockholm Sweden
2. Clinical Epidemiology Unit, Department of Medicine Karolinska Institutet Stockholm Sweden
3. Department of Obstetrics and Gynecology Visby County Hospital Visby Sweden
4. Department of Learning, Informatics, Management and Ethics, Unit for Medical Statistics Karolinska Institute Stockholm Sweden
5. Department of Women's and Children's Health Karolinska Institutet Stockholm Sweden
6. Division of Pediatric Surgery Astrid Lindgren Children's Hospital, Karolinska University Hospital Stockholm Sweden