Birth weight, postnatal weight gain, and adult body composition in five low and middle income countries.

OBJECTIVES To evaluate the associations between birth weight (BW), infancy, and childhood weight gain and adult body composition. METHODS Subjects included participants of five birth cohort studies from low and middle income nations (Brazil, Guatemala, India, Philippines, and South Africa; n = 3432). We modeled adult body composition as a function of BW and conditional weight gain (CW), representing changes in weight trajectory relative to peers, in three age intervals (0-12 months, 12-24 months, 24 months-mid childhood). RESULTS In 34 of 36 site- and sex-specific models, regression coefficients associated with BW and CWs were higher for adult fat-free than for fat mass. The strength of coefficients predicting fat-free mass relative to those predicting fat mass was greatest for BW, intermediate for CWs through 24 months, and weaker thereafter. However, because fat masses were smaller and showed larger variances than fat-free masses, weaker relationships with fat mass still yielded modest but significant increases in adult % body fat (PBF). CW at 12 months and mid-childhood tended to be the strongest predictors of PBF, whereas BW was generally the weakest predictor of PBF. For most early growth measures, a 1 SD change predicted less than a 1% change in adult body fat, suggesting that any health impacts of early growth on changes in adult body composition are likely to be small in these cohorts. CONCLUSIONS BW and weight trajectories up to 24 months tend to be more strongly associated with adult fat-free mass than with fat mass, while weight trajectories in mid-childhood predict both fat mass and fat-free mass.