Hypothesis: That a high hemoglobin threshold for transfusion in extremely low birth weight (ELBW) infants is associated with a lower rate of survival without severe morbidity (defined as one or more of retinopathy of prematurity, bronchopulmonary dysplasia, or periventricular leukomalacia/ventriculomegaly).

Primary Objective: To determine whether either a liberal or more restrictive threshold of hemoglobin level for red cell transfusion in ELBW infants is safer, by randomizing to either a high transfusion hemoglobin threshold or a low transfusion hemoglobin threshold.

Follow-up at a corrected age of 18 months represents a conventional age at which to first assess neurodevelopmental outcomes, and to predict long-term outcomes.

Inclusion Criteria:

• birth weight <1000g
• postnatal age <48 hours
• no transfusion beyond first 6 hours of life
• estimated gestational age of 30 completed weeks or less

Exclusion Criteria:

• infant considered non-viable by attending physician
• infant has cyanotic congenital heart disease
• infant's parents known to be opposed to blood transfusion
• either parent has hemoglobinopathies or congenital anemias
• infant has hemolytic disease
• infant has severe acute hemorrhage, severe shock, severe sepsis with coagulopathy or requires peri-operative transfusion
• prior treatment with or intention to treat with erythropoietin