1. Department of Pediatric and Adolescent MedicineAkershus University Hospital, Lørenskog, Norway
2. Institute of Clinical MedicineCampus Ahus, University of Oslo, Oslo, Norway
3. Department of NutritionInstitute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norway
4. Department of Neonatal Intensive CareWomen and Children's Division, Oslo University Hospital, Ullevål, Oslo, Norway
5. Oslo Centre of Biostatistics and Epidemiology, Department of Biostatistics, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norway
6. Department of Neonatal Intensive CareDivision of Paediatric and Adolescent Medicine, Oslo University Hospital, Rikshospitalet, Oslo, Norway
7. Department of Clinical ScienceUniversity of Bergen, Bergen, Norway