Background: An infant's iron intake in the first 6 months of life comes solely from milk intake. However, infants' feeding practices vary, and their association with infants' iron status and hematologic parameters has not been well studied. We aimed to evaluate how different infant feeding practices associate with iron status and hematologic parameters among 6-month-old Thai infants.
Methods: In a retrospective chart review, we identified 403 infants who attended a well-baby clinic and received laboratory screening for anemia (complete blood count and serum ferritin) at 6-month visits. Infants were categorized into four groups according to feeding practices. Hematologic parameters and incidence of anemia (hemoglobin [Hb]<11 g/dL), iron deficiency (ID; ferritin<12 ng/mL), and iron deficiency anemia (IDA; Hb<11 g/dL and ferritin<12 ng/mL) were compared between groups. Univariate and multiple logistic regression models were used to identify IDA associated factors among 6-month-old infants.
Results: In total, 105 infants were breastfed (BF), 78 were breastfed with iron supplementation (BI), 109 infants were mixed-fed (breast milk and formula) with or without iron supplementation starting at age 4 months (MF), and 111 infants were formula-fed (FF). The BF group had the highest incidence of anemia, ID, and IDA. Anemia was found in 38.1% of BF infants compared with 21.8% of BI, 19.3% of MF, and 16.2% of FF infants (p<0.001). ID was found in 28.6% of BF infants compared with 3.8% of BI, 3.7% of MF, and 0.9% of FF infants (p<0.001). IDA was found in 17.1% of BF infants compared with 2.6% of BI, 0.9% of MF, and 0.9% of FF infants (p<0.001). In multivariate logistic regression, higher weight gain during 0–6 months slightly increased the risk of IDA and higher birth weight slightly decreased this risk. BI, MF, and FF infants had 90.4%, 97.5%, and 96.9% decreased risk of IDA, respectively, with BF infants as a reference group.
Conclusion: The incidence of anemia, ID, and IDA at age 6 months was higher in BF than FF or partially BF infants. However, iron supplements in BF infants starting at 4 months significantly reduced their ID and IDA incidence.