Iron Status of the Moderate and Late Preterm Infant: A Prospective Cohort Study

Abstract

Guidelines on micronutrient supplementation in moderate to late preterm infants (MLP) are mostly extrapolated from those for smaller preterms, largely due to lack of systematic studies on physiological status in this special group of infants. Actual practices vary widely. We prospectively studied iron status by measurement of serum ferritin (SF) and haematological indices at 4 months corrected age in infants born between 32 and 36 weeks gestation (MLP), after they received 2 mg/kg/day oral iron from 6 weeks of postnatal age. Proportion of MLP having normal iron status (iron replete), i.e., neither iron deficiency (ID) nor iron excess was measured. ID anaemia, growth and development, risk factors for ID were also analysed. Of the 82 infants studied, 78% babies were late preterm. Seventy-four (90.3%) were iron replete (no deficiency or excess) at 4 months. High variability in SF levels (minimum of 9.8 to maximum of 252.2 μg/l) with median (IQR) of 57.45 μg/l (37.02-98.85) was noted in the entire cohort; and also within those who were iron deficient with median (IQR) of 17.50 μg/l (11.70-18.90). There was no difference in haematological indices of ID infants when compared to those with normal iron status. Inspite of oral iron supplementation with reasonable compliance, 8.5% MLP were iron deficient at 4 months corrected age. The high variability noted in SF levels could justify the need for monitoring iron status in this group of preterm infants. This could quintessentially aid individualization of iron supplementation advice.

Keywords: iron deficiency; iron deficiency anaemia; late preterm; moderate preterm; serum ferritin.