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Iron supplements do not improve infant development
Last reviewed: 02.07.2025
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Low-dose iron supplementation given to infants did not improve early development or iron status, a randomized controlled trial found.
Among 221 infants aged 4 to 9 months, randomization to iron supplements versus placebo did not improve Bayley III infant and toddler motor scores (adjusted mean difference [aMD] -1.07 points, 95% CI -4.69 to 2.55), cognitive scores (aMD -1.14, 95% CI -4.26 to 1.99), or language scores (aMD 0.75, 95% CI -2.31 to 3.82) at 12 months, reported Anna Chmielewska, MD, PhD, of Umea University in Sweden, and colleagues.
There was also no benefit at 12 months of age in reducing the risk of iron deficiency (RR 0.46, 95% CI 0.16-1.30) or iron deficiency anemia (RR 0.78, 95% CI 0.05-12.46), the team noted in the journal JAMA Pediatrics.
At 24 and 36 months, developmental outcomes were also similar between groups.
"Exclusive breastfeeding is recommended for approximately 6 months after birth," Chmielewska and colleagues write. "However, because the iron content of breast milk is low and iron intake from supplementary foods is often insufficient, prolonged breastfeeding is known to be associated with iron deficiency."
"The association between iron deficiency anemia and impairment of cognitive, motor and behavioural functions is well established, and the negative effects may be irreversible," they added.
However, high-quality evidence that iron supplementation makes a difference is lacking, leading to mixed recommendations for supplementation for breastfed infants after 4 months. The American Academy of Pediatrics recommends 1 mg/kg/day of iron for all infants who are predominantly or exclusively breastfed , beginning at 4 months of age until their diet can provide sufficient iron. European guidelines do not recommend routine iron supplementation for exclusively breastfed, healthy infants of normal birth weight.
"For primary care physicians and pediatricians," Chmielewska told MedPage Today, this study provides "more confidence in withholding iron supplements for healthy breastfed infants."
As for why the supplement didn't even affect iron levels, she added: "In this low-risk population, infants likely adjusted their iron intake between the end of the intervention (9 months) and the time of blood draw (12 months), so there was no difference at that time point."
The study included healthy, full-term identical infants for whom breastfeeding accounted for more than 50% of daily nutrition and who were free of anemia at 4 months of age.
The trial randomized 220 infants 1:1 to receive iron (1 mg/kg micronized microencapsulated ferric pyrophosphate mixed in water or breast milk) or placebo (maltodextrin) once daily from 4 to 9 months of age.
The study was conducted from December 2015 to May 2020 with follow-up until May 2023 in outpatient settings in Poland and Sweden. A total of 64.7% of infants completed all three Bayley assessments.
Limitations of the study include that of the eligible families, only 15% agreed to participate, "which may raise concerns about the generalizability of the results," Chmielewska and colleagues noted. They also acknowledged that developmental assessments were conducted using two different versions of the Bayley assessments in two countries (Poland and Sweden).