Iron status at 9 months of infants with low iron stores at birth

Objective: To determine the 9-month follow-up iron status of infants born with abnormally low serum ferritin concentrations. Study design: Ten infants of > 34 weeks' gestation with cord serum ferritin concentrations < 5th percentile at birth (< 70 μg/L) and 12 control infants with cord serum ferritin concentrations > 80 μg/L had follow-up serum ferritin concentrations measured at 9 ± 1 month of age. The mean follow-up ferritins, incidences of iron deficiency and iron-deficiency anemia, and growth rates from 0 to 12 months were compared between the two groups. Results: At follow-up, the low birth ferritin group had a lower mean ferritin than the control group (30 ± 17 vs 57 ± 33 μg/L; P = .03), but no infant in either group had iron deficiency (serum ferritin < 10 μg/L) or iron-deficiency anemia. Both groups grew equally well, but more rapid growth rates were associated with lower follow-up ferritin concentrations only in the low birth ferritin group (r = -0.52; P = .05). Both groups were predominantly breast-fed without iron supplementation before 6 months. Conclusions: Infants born with serum ferritin concentrations <5th percentile continue to have significantly lower ferritin concentrations at 9 months of age compared with infants born with normal iron status, potentially conferring a greater risk of later onset iron deficiency in the second postnatal year.