More than 30% of the very preterm infants given prophylactic iron supplementation after birth are still iron deficient at the time of their discharge from the hospital, suggests a recent study published in the Journal of Pediatrics.¹  

In a retrospective cohort study, Landry et al sought to determine the postdischarge iron levels in very preterm infants born between 2005 and 2018. The factors associated with iron deficiency were also ascertained in the study. The infants were administered iron supplements, as a routine, prophylactically from 2-4 weeks of chronological age. Iron levels were measured at 4 or 6 months corrected age to determine iron deficiency (serum ferritin <20 g/L at 4 months or <12 g/L at 6 months).

Out of the 411 infants included in the study, 132 (32.1%) had insufficient iron levels, while 11 (2.7%) had iron deficiency anemia. Between 2005 and 2011, the prevalence of iron deficiency was 37.6%. It declined to 25.8% from 2012 to 2018.

High blood pressure during pregnancy (p = .01) and gestational age less than 27 weeks (p = .02) were found to be significantly associated with iron deficiency. Infants who received combination feeding with breast milk and formula milk had lesser chances of being iron deficient compared to infants who received only formula milk.

The fetus accumulates its total body iron at birth during the third trimester of pregnancy. Hence, the iron stores in the preterm infants are predictably lower than the infants born full term. Because of maternal conditions such as maternal iron deficiency anemia, maternal smoking including factors in the NICU such as phlebotomy losses, the very preterm infant is already in a state of negative iron balance at the time of discharge. If the iron stores are not replenished, they are likely to be iron deficient as they grow older.²

This study has shown that iron deficiency in the very preterm infants is quite common regardless of prophylactic iron administration after birth. These observations call for close monitoring of iron stores (ferritin) during the first year of life. It has also determined risk factors for iron deficiency among the very preterm infants, the identification of which will also aid correction of iron deficiency.

References

1. Landry C, et al. Postdischarge iron status in very preterm infants receiving prophylactic iron supplementation after birth. J Pediatr. 2022 Aug;247:74-80.e2. doi: 10.1016/j.jpeds.2022.04.050.
2. Domellöf M, et al. Postdischarge iron requirements of the preterm infant. J Pediatr. 2015 Oct;167(4 Suppl):S31-5. doi: 10.1016/j.jpeds.2015.07.018.