Prospective Randomized Trial of Early Versus Late Enteral Iron Supplementation in Infants With a Birth Weight of Less Than 1301 Grams

Objectives. To examine whether early enteral iron supplementation (EI) would improve serum ferritin as a measure of nutritional iron status at 2 months of age and would prevent definite iron deficiency (ID) in infants with a birth weight of <1301 g. Methods. Infants were randomly assigned to receive enteral iron supplementation of 2 to 6 mg/kg/day as soon as enteral feedings of >100 mL/kg/day were tolerated (EI) or at 61 days of life (late enteral iron supplementation [LI]). Nutritional iron status was assessed: 1) at birth, 2) at 61 days of life, 3) when the infants reached a weight of 1.6 times birth weight, and 4) before blood was transfused at a hematocrit of <.25. ID was defined by any one of the following criteria: ferritin, <12 mg/L; transferrin saturation, <17%; or increase of absolute reticulocyte counts by >50% one week after the onset of enteral iron supplementation. Restrictive red cell transfusion guidelines were followed and all transfusions were documented. Erythropoietin was not administered. The primary outcome variables were: 1) ferritin at 61 days and 2) the number of infants with ID. Results. Ferritin at 61 days was not different between the groups. Infants in the LI group were more often iron-deficient (26/65 vs 10/68) and received more blood transfusions after day 14 of life. No adverse effects of EI were noted. Conclusions. EI is feasible and probably safe in infants with birth weight <1301 g. EI may reduce the incidence of ID and the number of late blood transfusions. ID may occur in very low birth weight infants despite early supplementation with iron and should be considered in the case of progressive anemia. Pediatrics 2000; 106:700 -706; preterm infant, iron supplementation, iron deficiency, blood transfusion.