The relative strength of weight and length at birth in contrast to social factors as determinants of height at 18 years in Brazil

Background: There is scarce information on the relative importance of measurements at birth and social factors in determining adult height. Aim: To assess the relative contribution of length and weight at birth, and social factors to height at 18 years. Methods: A total of 3470 boys born in Ribeirao Preto, Brazil, in 1978/1979 were reassessed at the time of military conscription. Anthropometric, demographic and social variables were collected concurrently and used in a multiple regression analysis. Results: A total of 2029 (61.3%) of the target population were assessed at 18 years. In the adjusted analysis, birth length, birth weight, social class, neighbourhood wealth of subject, maternal age and birth order were highly associated with height at 18 years. The results were similar when birth weight and length at birth were included as continuous or categorical variables. The differences in height due to length at birth were greater than those due to social factors. Conclusions: This study has demonstrated the lasting and greater effect of length and weight at birth on height in comparison to social factors, but social factors are still meaningful in their effects on height. Birth length has a marginal greater effect on final height than birth weight.