1 Department of Neonatal Intensive Care, Division of Paediatric and Adolescent Medicine, Rikshospitalet, Oslo University Hospital, Norway; Department of Nutrition, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Norway. Electronic address: kestro@ous-hf.no.
2 Department of Paraclinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Science, Oslo, Norway.
3 Department of Neonatal Intensive Care, Division of Paediatric and Adolescent Medicine, Ullevål, Oslo University Hospital, Norway.
4 Department of Pediatric and Adolescent Medicine, Akershus University Hospital and Institute for Clinical Medicine, Campus Ahus, University of Oslo, Nordbyhagen, Norway.
5 Norwegian Institute of Public Health, Oslo, Norway.
6 Department of Neonatal Intensive Care, Division of Paediatric and Adolescent Medicine, Rikshospitalet, Oslo University Hospital, Norway; Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Norway.
7 Department of Nutrition, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Norway.
8 Department of Nutrition, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Norway; Department of Haematology, Oslo University Hospital, Norway.