The Effect of Breastfeeding on Neuro-Development in Infancy

Cathal McCrory, Aisling Murray

The present study examines whether breastfeeding is associated with neuro-developmental advantages at 9 months of age on a standardised measure of infant development in a large cohort study of Irish children. It is hypothesised that if breast-milk confers an independent benefit, infants who were never breastfed will have reached fewer developmental milestones than those who were partially or exclusively breastfed, after controlling for putative confounding variables. Families with infants aged 9-months were recruited as part of a nationally representative sample for the birth cohort of the Growing Up in Ireland study (n = 11,134). Information was collected from mothers on breastfeeding practices, socio-demographic characteristics and developmental progress during a household interview. Parent-report items on development covered communication, gross motor, fine motor, problem solving and personal-social skills. Analysis of pass/fail status in each developmental domain using binary logistic regression showed a positive effect of any breastfeeding on gross motor, fine motor, problem solving and personal-social skills (but not communication) and these remained after adjustment for a range of confounding variables. There was, however, little evidence of a dose-response effect or advantage of exclusive over partial breastfeeding. A clear advantage of breastfeeding on infant development was demonstrated. However, the lack of a dose-response association on pass rates suggests that the breastfeeding effect may be confounded by other unobserved factors or that there is a critical threshold during which time the effect of breast milk may be particularly salient for bolstering brain development.