NEW YORK (Reuters Health) Jan 22 - Iron supplementation for very low birth weight (VLBW) infants does not increase their hematocrit levels or reduce their need for transfusions, a new study shows.
"In the absence of any other randomized trials to address this question, there is no evidence from clinical trials to support giving >2 mg/kg per day of iron to these infants," Dr. Tiffany A. Taylor and Dr. Kathleen A. Kennedy of The University of Texas Health Science Center at Houston Medical School write in a report online January 21 in Pediatrics.
VLBW infants have a steeper drop in hemoglobin levels one to three months after birth than normal-weight newborns because they undergo more blood tests, have red blood cells with a shorter life-span, and are growing very rapidly, the researchers explain.
Past research has shown that feeding preterm infants iron-supplemented formula or human milk will restore hemoglobin levels faster than feeding them with non-supplemented milk or formula.
VLBW infants may be at greater risk of iron-deficiency anemia than term infants, but because these babies frequently receive transfusions of red blood cells, this may delay or prevent anemia from developing, according to Dr. Taylor and Dr. Kennedy.
Complicating matters further, there are no valid tests for diagnosing iron-deficiency anemia in VLBW infants, who have higher corpuscular volume and ferritin levels than term infants, making these measures unreliable for diagnosing anemia.
"Notwithstanding this lack of evidence, the American Academy of Pediatrics recommends that preterm infants should receive a total iron intake of 2 mg/kg per day for infants between 1500 and 2500 g birth weight and 4 mg/kg per day for infants weighing <1500," the researchers note.
To test these recommendations, the researchers randomly assigned 150 infants who had reached 120 mg/kg/d of feeding before 32 weeks post-menstrual age (PMA) to receive routine fortification or routine fortification plus another 2 mg/kg of iron. Feeding infants with fortified milk or formula results in an intake of at least 2 mg/kg daily if the child is consuming at least 133 mL/kg daily.
Two of the infants died, and 100 received transfusion. There was no significant difference in hematocrit at 36 weeks PMA between the two groups (29.2% vs. 28.3%, p=0.21). Nor did the number of transfusions per subject or the reticulocyte counts differ. The researchers found no short-term adverse effects of iron supplementation.
They conclude that iron supplementation for VLBW infants above and beyond what they receive through fortification of formula or breast milk is not warranted, adding that, "If future trials are undertaken, a larger sample size or longer duration of treatment is recommended."