Effect of iron supplementation on psychomotor development of non-anaemic, exclusively or predominantly breastfed infants: a randomised, controlled trial

Effect of Low-Dose Iron Supplementation on Early Development in Breastfed Infants: A Randomized Clinical Trial

Importance

Breastfed infants are at risk of iron deficiency, which is associated with suboptimal development. There is a paucity of evidence on the effects of iron supplementation on child development, and current guidelines are divergent.

Objective

To assess whether daily iron supplementation, 1 mg/kg, between 4 and 9 months in exclusively or predominantly breastfed infants improves psychomotor development at 12 months.

Design, Setting, and Participants

This was a randomized, double-blind, placebo-controlled trial conducted between December 2015 and May 2020 with follow-up through May 2023 in an outpatient setting in Poland and Sweden. Participants were healthy singleton infants born at term with birth weight greater than 2500 g who were exclusively or predominantly breastfed (>50%) and did not have anemia (hemoglobin >10.5 g/dL) at age 4 months. Exclusion criteria included major illness, congenital anomaly, food allergy, and difficulty communicating with caregivers.

Interventions

Iron (micronized microencapsulated ferric pyrophosphate), 1 mg/kg, or placebo (maltodextrin) once daily from age 4 to 9 months.

Main Outcomes and Measures

The primary outcome was psychomotor development assessed by motor score of Bayley Scales of Infant and Toddler Development III at 12 months, adjusted for gestational age, sex, and maternal education. Secondary outcomes included cognitive and language scores at 12 months; motor, cognitive, and language scores at 24 and 36 months; iron deficiency (serum ferritin <12 ng/mL), and iron deficiency anemia (iron deficiency and hemoglobin <10.5 g/dL) at 12 months.

Results

Of 221 randomized infants (111 female), 200 (90%) were included in the intention-to-treat analysis (mean [SD] age, 12.4 [0.8] months). Iron supplementation (n = 104) compared to placebo (n = 96) had no effect on psychomotor development (mean difference [MD] for motor score, -1.07 points; 95% CI, -4.69 to 2.55), cognitive score (MD, -1.14; 95% CI, -4.26 to 1.99), or language score (MD, 0.75; 95% CI, -2.31 to 3.82) at 12 months. There were no significant differences at 24 and 36 months. The intervention did not reduce the risk for iron deficiency (relative risk [RR], 0.46; 95% CI, 0.16 to 1.30) or iron deficiency anemia (RR, 0.78; 95% CI, 0.05 to 12.46) at 12 months.

Conclusion and Relevance

No benefit was found with daily low-dose iron supplementation between 4 and 9 months with respect to psychomotor development, risk of iron deficiency, or iron deficiency anemia among breastfed infants in a setting of low risk of anemia.

Trial Registration

ClinicalTrials.gov Identifier: NCT02242188.

Six-Year Follow-up of Childhood Stimulation on Development of Children With and Without Anemia

BACKGROUND AND OBJECTIVES

Previously, in 30 Bangladeshi villages, 2 groups of children with iron-deficiency anemia (IDA) and nonanemic (NA) iron sufficiency aged 6 to 24 months participated in 2 parallel cluster randomized controlled trials of the effect of psychosocial stimulation on neurodevelopment. The intervention was composed of weekly play sessions at home for 9 months. All children with anemia received iron treatment of 6 months. The intervention improved the mental development of NA but not IDA groups. Six years after end line when the children were aged 8 to 9 years, we aimed to determine if benefits were sustained in the NA group or late-onset benefits emerged in the IDA group.

METHODS

We relocated 372 (90%) of the initial 412 children from all the clusters (villages), and assessed their IQ with the Wechsler Abbreviated Scale of Intelligence-II, motor development, and school achievement including math, spelling, and reading. Analyses were by intention-to-treat, adjusting for clustering.

RESULTS

There was a significant interaction between anemia groups (IDA/NA) and intervention on IQ. The intervention benefitted the NA group's Full-Scale IQ (effect size, 0.43 [95% confidence interval, 0.08-0.79]) and Perceptual Reasoning Index (effect size, 0.48 [95% confidence interval, 0.08-0.89]) but did not affect the IDA group's outcomes. No other outcomes were significant.

CONCLUSIONS

The benefits from early childhood psychosocial stimulation on the NA group's IQ, 6 years after intervention ended, adds to the limited evidence on the sustainability of benefits in low- and middle-income countries. Reasons for lack of effect in children with anemia are unknown.

Iron Deficiency, Cognitive Functions, and Neurobehavioral Disorders in Children

More than 25% of the world's population is affected by anemia, of which more than 50% suffers from iron deficiency anemia (IDA). Children below 7 years of age are the population group that is most vulnerable to iron deficiency. Iron is an essential element in brain metabolism. Iron deficiency can cause changes in neurotransmitter homeostasis, decrease myelin production, impair synaptogenesis, and decline the function of the basal ganglia. Therefore, IDA adversely affects cognitive functions and psychomotor development. Research has shown that iron deficiency is a frequent comorbidity in attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorder. Iron deficiency may also induce or exacerbate deficiency of other essential nutrients, which may have a negative impact on the developing brain and other organs in infants. Many nations of the world have programs to control IDA based on the use of iron supplementation, intake of fortified food and drinks, improved food safety, and monitoring of dietary diversity. Based on the current recommendations of the World Health Organization on cost-effectiveness (WHO-CHOICE), iron fortification and iron supplementation programs can be considered cost-effective or even highly cost-effective in most countries of the world to averting cognitive impairment.