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Cited by 350Breastfeeding Practices and InfluencesAdvanced Causal Inference TechniquesBirth, Development, and Health

What are the causal effects of breastfeeding on IQ, obesity and blood pressure? Evidence from comparing high-income with middle-income cohorts

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Brion, Marie-Jo A, Lawlor, Debbie A, Matijasevich, Alicia, Horta, Bernardo, Anselmi, Luciana, Araújo, Cora L, Menezes, Ana Maria B, Victora, Cesar G +1 more·2011·International Journal of Epidemiology
DOI 10.1093/ije/dyr020PMC PMC3147072
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Abstract

BACKGROUND: A novel approach is explored for improving causal inference in observational studies by comparing cohorts from high-income with low- or middle-income countries (LMIC), where confounding structures differ. This is applied to assessing causal effects of breastfeeding on child blood pressure (BP), body mass index (BMI) and intelligence quotient (IQ). METHODS: Standardized approaches for assessing the confounding structure of breastfeeding by socio-economic position were applied to the British Avon Longitudinal Study of Parents and Children (ALSPAC) (N ≃ 5000) and Brazilian Pelotas 1993 cohorts (N ≃ 1000). This was used to improve causal inference regarding associations of breastfeeding with child BP, BMI and IQ. Analyses were extended to include results from a meta-analysis of five LMICs (N ≃ 10 000) and compared with a randomized trial of breastfeeding promotion. Findings Although higher socio-economic position was strongly associated with breastfeeding in ALSPAC, there was little such patterning in Pelotas. In ALSPAC, breastfeeding was associated with lower BP, lower BMI and higher IQ, adjusted for confounders, but in the directions expected if due to socioeconomic patterning. In contrast, in Pelotas, breastfeeding was not strongly associated with BP or BMI but was associated with higher IQ. Differences in associations observed between ALSPAC and the LMIC meta-analysis were in line with those observed between ALSPAC and Pelotas, but with robust evidence of heterogeneity detected between ALSPAC and the LMIC meta-analysis associations. Trial data supported the conclusions inferred by the cross-cohort comparisons, which provided evidence for causal effects on IQ but not for BP or BMI. CONCLUSION: While reported associations of breastfeeding with child BP and BMI are likely to reflect residual confounding, breastfeeding may have causal effects on IQ. Comparing associations between populations with differing confounding structures can be used to improve causal inference in observational studies.

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  • Mendelian randomisation, using genetic information as a proxy for an exposure, could be used as a method to minimise confounding.

    “Mendelian randomisation, where genetic information is used as a proxy for an exposure of interest, could also be used as a method to minimise confounding (65).”

    From Association Between Cannabis and Psychosis: Epidemiologic Evidence (2016) · cites this paper as [65]

  • Important limitations to Mendelian randomisation currently include that genetic variants that robustly predict cannabis use have yet to be identified.

    “However, there are important limitations to Mendelian randomisation currently, in particular that genetic variants that robustly predict cannabis use have yet to be identified (65).”

    From Association Between Cannabis and Psychosis: Epidemiologic Evidence (2016) · cites this paper as [65]

    The Introduction describes Mendelian randomisation as a method that uses genetic information as instrumental variables. Our copy does not discuss cannabis use or whether genetic variants robustly predict it; searches for those terms and for limitations of Mendelian randomisation found no supporting passage. No page number was available for the Introduction passage. (LLM, conf=0.77)

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  • In cross-context comparisons, results are compared between two or more different populations, or the same population in two or more different contexts, under the a priori assumption that confounding structures differ between the contexts/populations.

    “In cross-context comparisons, results are compared between two or more different populations, or the same population in two or more different contexts (e.g. over different time periods), under the a priori assumption that confounding structures differ between the different contexts/populations.21”

    From Triangulation in aetiological epidemiology (2017) · cites this paper as [21]

  • Cross-context comparisons between a UK cohort and pooling of data from five low- or middle-income countries (LMIC) showed an inverse association of duration of breastfeeding with BMI in the UK cohort.

    “Cross-context comparisons between a UK cohort and pooling of data from five low- or middle-income countries (LMIC) showed an inverse association of duration of breastfeeding with BMI in the UK cohort”

    From Triangulation in aetiological epidemiology (2017) · cites this paper as [21]

  • In the cross-context comparison, SEP did not relate to breastfeeding in LMICs or was in the opposite direction to that seen in the UK; if an association in UK participants was due to SEP confounding, a null or opposite direction association would be expected in those from LMICs.

    “It was demonstrated that SEP did not relate to breastfeeding in the LMICs or was in the opposite direction (more affluent and educated women being less likely to breastfeed) to that seen in the UK (breastfeeding more common in the more affluent and educated women). If an association in UK participants was due to SEP confounding, we would expect a null or opposite direction association in those”

    From Triangulation in aetiological epidemiology (2017) · cites this paper as [21]

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Authors
Brion, M.-J. A., Lawlor, D. A., Matijasevich, A., Horta, B., Anselmi, L., Araújo, C. L., Menezes, A. M. B., Victora, C. G., & Smith, G. D.
Affiliations
Universidade Federal de Pelotas (BR)
Corresponding author
Brion, Marie-Jo A
ORCID
Venue
International Journal of Epidemiology
Publisher
Oxford University Press (OUP)
Published
2011-02-24
Volume
40
Issue
3
Pages
670-680
ISSN
  • 0300-5771 (ISSN-L)
  • 1464-3685
DOI
10.1093/ije/dyr020
PMC
PMC3147072
OpenAlex
W2168594544
Cited by
350
References
33
Citations by year
2026: 6 · 2025: 15 · 2024: 42 · 2023: 18 · 2022: 9 · 2021: 16 · 2020: 19 · 2019: 18 · 2018: 22 · 2017: 18 · 2016: 25 · 2015: 40 · 2014: 30 · 2013: 42 · 2012: 23
FWCI
24.00
Type
journal article
Language
en
Open access
Licence
cc-by-nc
Locations
  • International Journal of Epidemiology (publishedVersion, cc-by-nc)
  • Europe PMC (PubMed Central) (publishedVersion, cc-by-nc)
  • PubMed Central (publishedVersion, cc-by-nc)
  • PubMed (publishedVersion)
  • Bristol Research (University of Bristol) (publishedVersion)
  • Explore Bristol Research (submittedVersion, cc-by-nc)
  • UWA Profiles and Research Repository (UWA) (submittedVersion)
  • HighWire Press Open Archive (submittedVersion)
Funders
  • Wellcome Trust (085515, G0600705, 092731)
  • University of Bristol (G0600705)
  • Medical Research Council (G0600705)
Topics
  • Health Sciences › Medicine › Epidemiology › Breastfeeding Practices and Influences
  • Physical Sciences › Mathematics › Statistics and Probability › Advanced Causal Inference Techniques
  • Health Sciences › Medicine › Pediatrics, Perinatology and Child Health › Birth, Development, and Health
Keywords
breastfeeding, child intelligence, childhood body mass index, obesity, residual confounding, socioeconomic position, cross-cohort comparison, causal inference, breastfeeding promotion, Avon Longitudinal Study of Parents and Children, Pelotas cohort
MeSH terms
Blood Pressure, Blood Pressure Determination, Brazil, Breast Feeding, Child, Child, Preschool, Female, Humans, Income, Infant, Infant, Newborn, Intelligence, Intelligence Tests, Longitudinal Studies, Male, Obesity, Poverty, Pregnancy, Socioeconomic Factors, Cohort Studies, Body Mass Index, Prevalence, Evidence-Based Medicine

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