1. Department of Paediatrics, Hospital de la Santa Creu i Sant Pau, Barcelona. Spain.
2. Neonatal Unit, Hospital Universitario Quirón Dexeus, Barcelona, Spain.
3. Neonatal Unit, Hospital Clinic de Barcelona, Barcelona, Spain.
4. Department of Paediatrics, Medical School, University of Barcelona, Barcelona, Spain.
5. Division of Hematology, Molecular Biology Unit, Hospital Son Espases, Palma de Mallorca, Spain.
6. Neonatal Unit, Hospital de la Santa Creu i Sant Pau, Barcelona. Spain.
7. Neonatal Unit, Hospital Sant Joan de Déu, Esplugues de Llobregat, Barcelona, Spain.