Low birth weight infants are at risk for iron deficiency (ID). Most LBW infants have marginally low birth weight (MLBW, 2000–2500 g) and it is not known whether they benefit from iron supplements. The objective of this trial was to study the effects of iron supplementation in MLBW infants.
In a randomized controlled trial, we assigned 285 healthy, MLBW infants to receive iron supplements at a dose of 0 (placebo), 1, or 2 mg/kg per day between 6 weeks and 6 months of age. Hemoglobin levels, ferritin levels, transferrin saturation, mean cell volume, and transferrin receptor levels were analyzed at 6 months. Growth and morbidity were monitored.
Iron supplementation resulted in significant dose-dependent effects on hemoglobin and all iron status indicators at 6 months. The prevalence of ID at 6 months was 36% in the placebo group, 8.2% in the 1 mg/kg per day group, and 3.8% in the 2 mg/kg per day group (P < .001). The prevalence rates of ID anemia (IDA) were 9.9%, 2.7%, and 0%, respectively (P = .004). Among infants who were exclusively breastfed at 6 weeks, the prevalence of IDA was 18% in the placebo group. There were no significant differences between groups in growth or morbidity.
MLBW infants have relatively high risks of ID and IDA, especially if they are breastfed. Iron supplementation at 2 mg/kg per day from 6 weeks to 6 months reduces this risk effectively, with no short-term adverse effects on morbidity or growth.