Infant feeding and child cognition and behaviour: quantifying pathways to understand the link in the CHILD cohort study
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Date
2024-10-31
Authors
Turner, Sarah
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Abstract
Introduction: Research has shown that breastfeeding is related to improved child cognitive and behavioural outcomes (CBOs), however, few studies have examined pathways to explain these associations. The objectives of this dissertation are to examine 1) the relationship between breastfeeding and child CBOs and 2) four pathways to help explain this link: breast milk components, the gut microbiome, maternal depression, and the parent-child relationship.
Methods: This dissertation uses data from the CHILD cohort study (n=2,342 parent-infant dyads). Infant feeding practices, maternal depression and parent-child relationship were repeatedly measured from birth to two years using standardized questionnaires. Breast milk samples, collected at 3-4 months, were analyzed for fatty acids and human milk oligosaccharides (HMOs); stool samples, collected a 3 and 12 months, were analyzed for microbiome diversity and composition. The Bayley Scales of Infant and Toddler Development and the Child Behaviour Checklist were used to measure child CBOs at 2 and 5 years. Linear regression, adjusting for confounders, was used to assess the relationships between infant feeding, breast milk components and child CBOs. Interaction terms were used to investigate moderation by child sex, family socioeconomic risk or maternal secretor status. Mediation analysis was used to assess the role of the gut microbiome, maternal depression and the parent-child relationship.
Results: Longer breastfeeding duration and more exclusive breastfeeding were related to better child CBOs with the strongest associations observed for behaviour at five years, and stronger associations for those with more socioeconomic risk factors. Higher concentrations of the HMOs 3’-sialyllactose and lacto-N-hexaose were related to better language and cognitive scores, respectively. The gut microbiome did not mediate the relationship between infant feeding and CBOs; however, maternal depression and the parent-child relationship were mediators of this association.
Conclusion: Breast milk components as well as maternal mental health and the parent-child relationship all contribute to the relationship between infant feeding and CBOs, with the parent-child relationship having the strongest effect size in mediation models. This research can provide evidence for policies and programs to support breastfeeding, maternal mental health and a positive parent-child relationship and inform the development of supplements for babies who cannot be breastfed.
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breastfeeding, child neurodevelopment, milk composition, maternal depression, parent-child relationship, infant gut microbiome