1. Department of Neonatology, Nordsjælland Hospital, 3400 Hillerød, Denmark
2. Department of Public Health, Section of of Biostatistics, University of Copenhagen, 1352 Copenhagen, Denmark
3. Department of Neonatology, Herlev Hospital, 2730 Herlev, Denmark
4. Department of Neonatology, Hvidovre Hospital, 2650 Hvidovre, Denmark
5. Department of Biochemistry and Immunology, Vejle Sygehus, University of Southern, 7100 Vejle, Denmark
6. Department of Neonatology, Copenhagen University Hospital—Rigshospitalet, 2100 Copenhagen, Denmark
7. Department of Ophthalmology, Copenhagen University Hospital—Rigshospitalet, 2100 Copenhagen, Denmark