Do infants who are breastfed score higher on IQ tests than infants who are formula-fed?

Last updated: February 20, 2022
Yes. Both studies in this list that examine the question agreed on this conclusion. We identified both studies as literature reviews, which are studies that review and often evaluate the findings of many studies on a question. This gives us more confidence that the answer is correct.
This short answer was generated by aggregating the answers that each of the studies below gave to the question (as indicated by State of K members) and adjusting for source quality and other factors. If key studies are missing or the answers attributed to individual studies are incorrect, the above answer could be wrong. For medical questions, don't rely on the information here. Consult a medical professional.
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Chart summary of 2 studies examining this question

All answers are assigned by State of K users. The label Couldn't Identify means that State of K was not able to determine whether a study answers the question "yes" or "no". This could be due to several factors. One possibility is that a study found some evidence to indicate that the answer to the question is "yes" and some evidence to indicate that the answer is "no". This often happens when a study uses two or more proxies to study the same phenomenon (i.e. firearm sales figures and self-reported firearm ownership rates as proxies for the prevalence of firearms) and the proxies yield different results when looking for correlations with another phenomenon (i.e. firearm-related deaths). Alternatively, the label may be applied if the phenomenon under study (i.e. whether breast milk improves cognitive function) is true for one group, but not another (i.e. true for girls, but not for boys). Yet another possibility is that a study found there was insufficient evidence to reach a conclusion regarding the question. Finally, the full text or abstract of a study may not have been written clearly or was inaccessible. This would make it difficult to determine how a study answered a question.

All labels of Literature Reviews and source quality are assigned by State of K. All labels of High Quality Source are assigned based on whether the publication in which the article appeared was ranked as Q1 by Scimago Institutions Rankings. Certain well-regarded think tanks are also given this label.

Literature Reviews
Although we recommend you consider all of the studies below, we believe the following studies are literature reviews, which survey and evaluate many studies on this question:

SUMMARIES OF STUDIES
Total studies in list: 2
Sorted by publication year
1
Impact of the Duration of Breastfeeding on the Intelligence of Children: A Systematic Review with Network Meta-Analysis
"Objective: To evaluate the impact of the duration of breastfeeding on the intelligence of children.Materials and Methods: Eight electronic databases were searched to identify studies that investigated the impact of breastfeeding on the intelligence of children. Data were pooled, and the ratio of means (RoM) and the corresponding 95% confidence interval (95% CI) were calculated using a pairwise meta-analysis and network meta-analysis. Risk of bias was assessed using a tool developed by the CLARITY group. Data were analyzed using R version 3.5.1.Results: A total of 15 studies with 12,316 subjects were included in the review. Half of the studies were at low risk of bias. A meta-analysis indicated that breastfed children had a score 1.04-fold higher in intelligence tests compared with those that had never been breastfed (RoM: 1.04, 95% CI: 1.02–1.06, p < 0.05). Evidence from a network meta-analysis indicated that breastfeeding for ≤6 months resulted in score 1.04-fold higher in intelligence tests (RoM: 1.04, 95% CI: 1.03–1.06, p < 0.05) and children breastfed for >6 months had a score 1.06-fold higher (RoM: 1.06, 95% CI: 1.05–1.08, p < 0.05) than children that had never been breastfed. Thus, breastfeeding for >6 months demonstrated a slightly higher score than breastfeeding for ≤6 months (RoM: 1.02, 95% CI: 1.00–1.04, p < 0.05).Conclusion: Breastfeeding could significantly improve the intelligence of children, with a duration of >6 months showing a slight but significantly higher intelligence score than for ≤6 months."
AUTHOR
Liangying Hou
PUBLISHED
2021 Breastfeeding Medicine
Literature Review
High Quality Source
Yes
Yes
2
Breastfeeding and Intelligence: A Systematic Review and Meta-Analysis
"Aim: This study was aimed at systematically reviewing evidence of the association between breastfeeding and performance in intelligence tests.Methods: Two independent searches were carried out using Medline, LILACS, SCIELO and Web of Science. Studies restricted to infants and those where estimates were not adjusted for stimulation or interaction at home were excluded. Fixed- and random-effects models were used to pool the effect estimates, and a random-effects regression was used to assess potential sources of heterogeneity.Results: We included 17 studies with 18 estimates of the relationship between breastfeeding and performance in intelligence tests. In a random-effects model, breastfed subjects achieved a higher IQ [mean difference: 3.44 points (95% confidence interval: 2.30; 4.58)]. We found no evidence of publication bias. Studies that controlled for maternal IQ showed a smaller benefit from breastfeeding [mean difference 2.62 points (95% confidence interval: 1.25; 3.98)]. In the meta-regression, none of the study characteristics explained the heterogeneity among the studies.Conclusion: Breastfeeding is related to improved performance in intelligence tests. A positive effect of breastfeeding on cognition was also observed in a randomised trial. This suggests that the association is causal."
AUTHOR
Bernardo L. Horta
PUBLISHED
2015 Acta Paediatrica
Literature Review
Yes
Yes