Feeding Type at 6-12 Months and Early-Life Iron-Related Hematologic Changes in Infants: A Longitudinal Birth Cohort...

The World Health Organization recommends continued breastfeeding for up to 2 years of age. However, because breast milk contains less iron than formula milk, prolonged exclusive breastfeeding may increase the risk of iron deficiency anemia. This study aimed to compare iron status and growth outcomes at 12 and 36 months based on feeding methods during the 6-12-month period.

In this prospective birth cohort study, we followed 126 children from birth to 36 months. Participants were categorized into breastfeeding (BF, n = 21), formula feeding (FF, n = 62), and mixed feeding (MF, n = 43) groups according to milk feeding over 6-12 months of age. Anthropometric measurements and iron parameters were compared among groups at 12 and 36 months.

At 12 months, the BF group had significantly lower weight and height compared to the MF group. Hemoglobin, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration were significantly lower in the BF group than in the FF and MF groups, while red cell distribution width was significantly higher in the BF group. At 36 months, no differences in anthropometrics or iron parameters were observed among the groups.

Infants breastfed without formula from 6 to 12 months showed lower iron-related hematologic parameters at 12 months, which largely resolved by 36 months. These findings highlight late infancy as a potentially vulnerable period for insufficient iron intake and support the importance of adequate iron supplementation and timely introduction of iron-rich complementary foods during this critical developmental stage.