Timing of Complementary Feeding Introduction and Adiposity Throughout Childhood

OBJECTIVES: To examine associations of the timing of complementary feeding (CF) introduction with adiposity throughout childhood. METHODS: We studied 1013 children from Project Viva. Our exposure was CF introduction, categorized as <4 months (19%), 4 to <6 months (68%; reference group), and ≥6 months of age (14%). Our outcomes included adiposity measures in midchildhood (mean: 7.9 years; SD 0.8; n = 896) and early adolescence (mean: 13.2 years; SD 0.9; n = 850). We used linear regression models adjusted for potential confounders and ran separate models for infants who were breastfed at least partly for ≥4 months (categorized as breastfed; 69%) and infants who were never breastfed or stopped breastfeeding at <4 months (categorized as formula fed; 31%). RESULTS: CF initiated at <4 months was associated with higher adiposity in midchildhood in breastfed children; associations persisted into adolescence for waist circumference, truncal fat mass, and the sum of subscapular and triceps skinfolds (eg, waist circumference: confounder-adjusted β 2.97 [95% confidence interval (CI) 0.47 to 5.47] cm). The effect estimates were larger in formula-fed children, with more associations persisting into adolescence (eg, waist circumference: adjusted β 3.42 [95% CI 0.12 to 6.71] cm). CF initiated at ≥6 months was associated with a higher subscapular/triceps skinfold ratio in midchildhood and adolescence (adjusted β 0.13 [95% CI 0.02 to 0.25]) in formula-fed children. CONCLUSIONS: We found associations of early CF introduction with higher adiposity measurements in breastfed and formula-fed children and associations of late introduction of CF with higher adiposity in formula-fed children.