['The associations of birth size, rate of growth during infancy, and odds of childhood overweight have not yet been thoroughly investigated in contemporary cohorts in low- and middle-income countries. The primary aim of this study was to evaluate the influence of birth size (using body mass index at birth) and accelerated growth during infancy (defined as upward growth curve percentile crossing between birth and age 1 year) on the odds of childhood overweight. A secondary goal was to characterize the sociodemographic correlates of accelerated growth during infancy.', 'Observational prospective cohort.', 'Participants were 163 children and their mothers living in semiurban Mexico who were originally recruited between 1997 and 2000 and followed until 2005.', 'Primary outcome was childhood overweight (as assessed by body mass index). Secondary outcome was accelerated growth during infancy.', 'Multivariate linear regression and logistic regression were used to determine the associations among birth size, accelerated growth, and childhood overweight.', 'Increased size at birth and accelerated growth during the first year of life increased the odds of childhood overweight (odds ratio [OR] 7.62, P<0.0005 and OR 2.23, P<0.05, respectively). The effect of accelerated growth on odds of childhood overweight varied by size at birth (OR for interaction term 0.63, P<0.05). Living in a "dual burden" household, where the child was underweight at birth and the mother was overweight 4 to 6 years after birth, was associated with accelerated growth during the first year of life.'] Are birth size and accelerated growth during infancy associated with increased odds of childhood overweight in Mexican children?