Résumé
OBJECTIVE: To investigate the dose-response relationship between breastfeeding duration and cognitive development in French preschool children. STUDY DESIGN: In the French EDEN Mother-Child Cohort Study, we evaluated language ability with the Communicative Development Inventory (CDI) in 1387 2-year-old children and overall development with the Ages and Stages Questionnaire (ASQ) in 1199 3-year-old children. Assessments were compared between breastfed and non-breastfed children and also according to breastfeeding duration in multivariable linear models, controlling for a wide range of potential confounders. We tested departure from linearity. RESULTS: After adjustments, ever-breastfed children scored 3.7 ± 1.8 (P = .038) points higher than never-breastfed children on the CDI and 6.2 ± 1.9 (P = .001) points higher on the ASQ. Among breastfed children, exclusive and any-breastfeeding durations were positively associated with both CDI and ASQ scores. The fine motor domain of ASQ was associated with any-breastfeeding duration, and the problem solving domain with exclusive-breastfeeding duration. We did not observe significant departures from linearity. No interactions were found between the child's sex, parental education or socioeconomic status, and breastfeeding duration. CONCLUSION: Longer breastfeeding duration was associated with better cognitive and motor development in 2- and 3-year-old children and a dose-response relationship was suggested.