Anemia in preterm infants.

Abstract

During fetal life, hemoglobin concentration increases from a level of 9 g/dL at l0 weeks9 to 14 to 15 g/dL at 22 to 24 weeks9 gestation. By the middle of the third trimester, concentrations close to those observed at birth (16 to 17 g/dL) are reached, and little additional change occurs. As a result, cord hemoglobin concentrations in term and preterm newborns are very similar, with the possible exception of the most extremely preterm infants. Immediately after birth, the hemoglobin concentration begins to rise from the combined effects of placental transfusion and the postnatal readjustment of plasma volume. At approximately 8 to 12 hours of life, the hemoglobin plateaus at levels 1 to 2 g/dL above those observed at birth (about 18 g/dL).