The breastfeeding triangle: crawling as a mediator of breastfeeding duration and cognitive development at 2 years of age
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Bodnarchuk, Jennifer L.
Longer breastfeeding durations may enhance cognition and accelerate motor development; motor development, and in particular, crawling, may lead to dramatic changes in cognition. Based on these empirical relations, the hypothesis that crawling mediates breastfeeding duration and cognitive outcome was tested. Specifically, it was hypothesized that longer breastfeeding durations would significantly predict both earlier crawling and higher cognitive scores at 2 years of age, that earlier crawling would also predict higher cognitive scores, and that earlier crawling would account for part of the relationship between longer breastfeeding durations and higher cognitive scores. A sample of 44 full term infants from Winnipeg, Manitoba was followed longitudinally between birth and 2 years of age. Data on breastfeeding duration and crawling were collected through daily parent checklists, with supplemental breastfeeding information obtained via questionnaires. Near the toddlers’ 2nd birthdays, cognitive abilities were assessed with the MacArthur Communicative Development Inventory: Words and Sentences (Fenson et al., 1993) and the Parent Report of Children’s Abilities (Saudino et al., 1998). All 3 key variables were measured on continuous scales, and a mediational analysis based on Baron and Kenny’s (1986) classic approach of 3 regressions was used. Several covariates were considered for inclusion in the regressions, but none reached significance in preliminary tests and thus, were not included. In the first 2 regression analyses, exclusive and partial breastfeeding durations significantly predicted neither cognitive scores (p = .59) nor age of crawling attainment (p = .41). The 3rd regression analysis showed a significant, small-to-medium effect size for earlier crawling attainment predicting higher cognitive scores (p < .05, adjusted R2 = .09). However, crawling onset had no effect on the breastfeeding-cognition link. The overall test of the mediation was inconclusive, due to low power. The significant finding between age of crawling onset and cognitive outcomes at 2 years of age may be due to earlier crawling altering the course of development, to reverse causation whereby more cognitively advanced infants are motivated to crawl sooner, or to a 3rd variable affecting both crawling and cognition. Future research should continue to explore motor and cognitive connections in infant development.
breastfeeding, motor development, infancy, infant development, cognitive development, mediation, crawling