 POPULATION All preterm infants born with gestational age 32 weeks who are admitted to one of the participating NICUs are eligible for inclusion. The participating departments are all level III Neonatal Intensive Care Units. Three are situated in an academic hospital Rotterdam, Nijmegen and Maastricht and one in a non--academic hospital Veldhoven. Patients admitted to the 4 NICUs consist of both inborn and outborn neonates with different gestational ages 24--42 weeks. All admitted patients need intensive or high care treatment. Most patients will be admitted on the first postnatal day, but sometimes are referred at older post natal ages 14 days to the NICU. 