title: Full breast-feeding for at least four months has differential effects on growth before and after six months of age among children in a Mexican community.
abstract: This study examines the relationship between breast-feeding and growth from 0 to 6 and 6 to 20 mo among 185 children in a Mexican community. Infants from a previous 6-mo longitudinal study were followed up for additional anthropometric measurements at a mean age of 19.9 mo. Size at 6 mo and at follow-up were modeled as outcomes of whether infants were fully breast-fed (exclusively or predominantly breast-fed) for at least 4 mo, controlling for size at birth and 6 mo, respectively, and potential confounders. From birth to 6 mo, fully breast-fed infants had ponderal index increments of 0.07 units larger (P = 0.04) than comparison infants. There were no differences in weight. For length, an interaction between full breast-feeding and socioeconomic status (SES) was found, with fully breast-fed infants of low SES growing more than comparison infants, whereas the opposite was seen at upper SES levels. From 6 to 20 mo, fully breast-fed infants had weight and length increments of 0.53 cm (P < 0.001) and 0.72 kg (P = 0.01) smaller than those of comparison infants. For ponderal index, an interaction between mother's education and breast-feeding revealed an inverted U-shaped response across levels of education. Additionally, logistic regressions of monthly breast-feeding on lagged measurements revealed that relatively heavier infants had higher odds of being fully breast-fed at 2 and 3 mo. Our findings indicate that the benefits of full breast-feeding on growth may be most pronounced early in life. Further research of unmeasured confounders may explain the association of full breast-feeding with slower growth beyond 6 mo.
authors.affiliation: Department of Nutrition, University of North Carolina at Chapel Hill, USA. roberts9@email.unc.edu
authors.forename: C L
authors.initials: CL
authors.lastname: Eckhardt
authors.forename: J
authors.initials: J
authors.lastname: Rivera
authors.forename: L S
authors.initials: LS
authors.lastname: Adair
authors.forename: R
authors.initials: R
authors.lastname: Martorell
mesh_terms: D001835:Body Weight; D001942:Breast Feeding; D005500:Follow-Up Studies; D006128:Growth; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008800:Mexico; D013997:Time Factors