Long-term behavioural consequences of infant feeding: The limits of observational studies

Michael S. Kramer, Eric Fombonne, Lidia Matush, Natalia Bogdanovich, Mourad Dahhou, Robert W. Platt

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


Observational (non-experimental) studies of the association between infant feeding and subsequent child or adult behaviour are prone to residual confounding by subtle differences in psychological attributes and interactional styles of mothers who breast feed vs. those who formula-feed. We followed up 13 889 6.5-year-old Belarusian children who participated in a large cluster-randomised trial of a breast-feeding promotion intervention. Behaviour was evaluated using the Strengths and Difficulties Questionnaire (SDQ), completed independently by the children's parents and teachers. We compared the results of experimental (intention-to-treat, ITT) and observational analyses (based on feeding actually received), both adjusted for clustering. Observational analyses were additionally adjusted for geographical region, urban vs. rural residence, child's sex, age at follow-up, birthweight, and maternal and paternal education. No differences between the randomised experimental vs. control groups were observed in ITT analyses. In contrast, small but statistically significant associations with weaning prior to 3 months were observed for parent and teacher SDQ scores on total difficulties, conduct problems and hyperactivity, even after multivariable adjustment. The absence of associations based on ITT analyses, in contrast with the significant associations based on observed breast-feeding duration, strongly suggests that the latter are biased by residual confounding.

Original languageEnglish (US)
Pages (from-to)500-506
Number of pages7
JournalPaediatric and Perinatal Epidemiology
Issue number6
StatePublished - Nov 2011
Externally publishedYes


  • RCT
  • breast feeding
  • child behaviour
  • weaning

ASJC Scopus subject areas

  • Epidemiology
  • Pediatrics, Perinatology, and Child Health


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