Effects of Transfusion Thresholds on Neurocognitive Outcome of Extremely Low Birth Weight Infants

Inclusion Criteria: * Infants with a birth weight of 400 - 999g Exclusion Criteria: * Missing written parental consent. * Gestational age \> 29 + 6/7 weeks * Major congenital anomalies (including chromosomal aberrations, cyanotic congenital heart defects, syndromes likely affecting long-term outcome, and major congenital malformations requiring surgical correction during newborn period). * Infants who died before 48 hours, infants in whom the clinical decision to withhold intensive care was made, infants who were not considered viable * Participation in another study with ongoing use of an unlicensed investigational product from 28 days before study enrollment until the end of the study