Non Breast-Milk-Fed Very Preterm Infants Are at Increased Risk of Iron Deficiency at 4-6-Months Corrected Age: A Retrospective Population-Based Cohort Study.

Iron supplementation is routinely recommended for breast-milk-fed preterm infants. However, the Canadian Pediatric Society recommends no additional iron supplementation for preterm infants fed primarily with iron-rich formula. Other pediatric societies don't provide specific guidance on supplemental iron for formula-fed preterm infants. This study investigated how feeding type influences iron status of very preterm infants at 4-6-months corrected age (CA). A retrospective cohort study was conducted using a population-based database on all very preterm infants (<31 weeks gestational age) born in Nova Scotia, Canada from 2005-2018. Information about feeding type, iron intake from formula, supplemental iron therapy and iron status at 4-6-months CA was extracted. Iron deficiency (ID) was defined as serum ferritin <20 and <12 µg/L at 4-and 6-months CA, respectively. Of 392 infants, 107 were "breast-milk-fed" (exclusively or partially) and 285 were "not breast-milk-fed" (exclusively fed with iron-rich formula) at 4-6-months CA. Total daily iron intake was higher in the non-breast-milk-fed group (2.6 mg/kg/day versus 2.0 mg/kg/day). Despite this, 36.8% of non-breast-milk-fed infants developed ID versus 20.6% of breast-milk-fed infants. ID is significantly more prevalent in non-breast-milk-fed infants than breast-milk-fed infants despite higher iron intake. This suggests the need to revisit recommendations for iron supplementation in non-breast-milk-fed preterm infants.

Postdischarge Iron Status in Very Preterm Infants Receiving Prophylactic Iron Supplementation after Birth.

OBJECTIVE: To determine postdischarge iron status and associated factors in very preterm infants. STUDY DESIGN: A retrospective cohort study was conducted through a provincial database on all very preterm infants born in Nova Scotia between 2005 and 2018. As a standard of care, all infants received prophylactic iron supplements starting at 2-4 weeks of chronological age and were tested for iron deficiency at 4 or 6 months corrected age. Iron deficiency was defined as serum ferritin <20 g/L at 4 months or <12 g/L at 6 months. Multivariate logistic regression analysis identified factors associated with iron deficiency. RESULTS: Among 411 infants, 132 (32.1%) had iron deficiency and 11 (2.7%) had iron deficiency anemia. The prevalence of iron deficiency decreased over time, from 37.6% in 2005-2011 to 25.8% in 2012-2018. Gestational hypertension in the mother (P = .01) and gestational age <27 weeks (P = .02) were independent risk factors for iron deficiency. In addition, the odds of iron deficiency were lower in the mixed-fed group (ie, with breast milk and formula combined) compared with the exclusive formula-fed group (P = .01). CONCLUSIONS: Iron deficiency was prevalent in 32% of the very preterm infants despite early iron prophylaxis. These results demonstrate the importance of monitoring iron stores during preterm follow-up. Information about risk factors is important to mitigate iron deficiency in very preterm infants.