Catch-up de peso e índice de massa corporal em escolares de coortes de nascimento de duas cidades brasileiras

Abstract

Introduction: Intrauterine growth restriction (IUGR) and preterm birth (PT) are considered to be public health problems in developing countries. The occurrence of catch-up favors the ability of these infants to obtain equivalent growth to that of infants born without IUGR and at term. Objective: To assess the influence of IUGR and of PT on the occurrence of catch-up in weight and BMI in schoolchildren from two birth cohorts from cities with contrasting socioeconomic conditions in the Northeast and Southeast of Brazil. Method: A total of 1,463 children were studied, from whom information was collected at birth and at school age in 1994 and 2004/2005 in Ribeirão Preto, SP (RP) and in 1997/1998 and 2005/2006 in São Luís, MA (SL). The response variable was defined as the difference in weight and BMI between the Z-score of the schoolchild and the Z-score at birth. A change in Z-score ≥ 0.67 was considered to be catch-up. The explanatory variable was divided into four categories: without IUGR and at term (NIUGR-T), only IUGR (IUGR-T), only PT (NIUGR-PT), and PT plus IUGR (IUGR-PT). Estimates of the relative risk for catch-up in weight were obtained by logistic regression in separate models for each city. Results: RP children had a greater proportion of both catch-up than SL children. In RP, 90.8% of IUGR-PT and 70.8% of NIUGR-PT (it was more frequent in pre-terms, restricted or not) caught up in weight at school age. In SL, the NIUGR-PT and IUGR-T caught up in a similar way. There was no difference between genders. Regarding marital status, in RP, no difference was found, however, in SL, the odds of catching up at 7 years old was 65% lower for those schoolchildren whose mothers did not have a partner. Having only one child, both in RP and in SL, increased almost twofold (OR=1.89 in RP and 1.83 in SL) the odds of the schoolchild catching up; and receiving up to 5 times the monthly minimum wage decreased by 50% the odds of catching up in SL, although no difference was found in RP. The head of the family’s occupation being unqualified manual labor or unemployed decreased by half the odds of catching up in both cities. Maternal age and education level were not associated to catchup in school age. Conclusion: In both cities, children born preterm with/without IUGR had a greater proportion of catch-up in weight and without IUGR and at term in BMI.