1. Research Unit/Department of Obstetrics and Gynaecology Sørlandet Hospital HF Kristiansand/Arendal Norway
2. Institute of Clinical Medicine, Faculty of Medicine University of Oslo Oslo Norway
3. Department of Public Health and Nursing, HUNT Centre for Molecular and Clinical Epidemiology Norwegian University of Science and Technology Trondheim Norway
4. Department of Endocrinology, Clinic of Medicine, St Olav's Hospital Trondheim University Hospital Trondheim Norway
5. Oslo Centre of Biostatistics and Epidemiology, Research Support Services Oslo University Hospital Oslo Norway
6. Faculty of Health Sciences Oslo Metropolitan University Oslo Norway
7. Department of Obstetrics, Division of Obstetrics and Gynaecology Oslo University Hospital Oslo Norway