1. Division of Epidemiology, Norwegian Institute of Public Health; Oslo Norway
2. Department of Global Public Health and Primary Care; University of Bergen; Bergen Norway
3. Section of Medical Informatics; University of Oslo; Oslo Norway
4. Department of Obstetrics and Gynecology; Stavanger University Hospital; Stavanger Norway
5. National Center for Fetal Medicine, Department of Obstetrics and Gynecology; St Olav's University Hospital; Trondheim Norway
6. Department of Laboratory Medicine, Children's and Women's Health; Norwegian University of Science and Technology; Trondheim Norway