Abstract
In developed countries, children with intrauterine growth restriction (IUGR) or born preterm (PT) tend to achieve catch-up growth. There is little information about height catch-up in developing countries and about height catch-down in both developed and developing countries. We studied the effect of IUGR and PT birth on height catch-up and catch-down growth of children from two cohorts of liveborn singletons. Data from 1,463 children was collected at birth and at school age in Ribeirão Preto (RP), a more developed city, and in São Luís (SL), a less developed city. A change in z-score between schoolchild height z-score and birth length z-score≥0.67 was considered catch-up; a change in z-score≤−0.67 indicated catch-down growth. The explanatory variables were: appropriate weight for gestational age/PT birth in four categories: term children without IUGR (normal), IUGR only (term with IUGR), PT only (preterm without IUGR) and preterm with IUGR; infant's sex; maternal parity, age, schooling and marital status; occupation of family head; family income and neonatal ponderal index (PI). The risk ratio for catch-up and catch-down was estimated by multinomial logistic regression for each city. In RP, preterms without IUGR (RR = 4.13) and thin children (PI<10th percentile, RR = 14.39) had a higher risk of catch-down; catch-up was higher among terms with IUGR (RR = 5.53), preterms with IUGR (RR = 5.36) and children born to primiparous mothers (RR = 1.83). In SL, catch-down was higher among preterms without IUGR (RR = 5.19), girls (RR = 1.52) and children from low-income families (RR = 2.74); the lowest risk of catch-down (RR = 0.27) and the highest risk of catch-up (RR = 3.77) were observed among terms with IUGR. In both cities, terms with IUGR presented height catch-up growth whereas preterms with IUGR only had height catch-up growth in the more affluent setting. Preterms without IUGR presented height catch-down growth, suggesting that a better socioeconomic situation facilitates height catch-up and prevents height catch-down growth.
Highlights
Catch-up and catch-down growth are defined as height or weight growth above or below the statistical limits of normality for age [1,2]
In Ribeirao Preto (RP) follow-up rates were lower among women who cohabited, who were aged,20 or from 20 to 34 years, who had #4 or $12 years of schooling, among those belonging to families whose head had an unskilled manual occupation or was unemployed and whose family income was,3 minimum wages
In Sao Luıs (SL) women with $12 years of schooling, primiparous women, those belonging to families whose heads were engaged in non-manual occupations and whose family income was less than three minimum wages, and boys had lower follow-up rates compared to their counterparts
Summary
Catch-up and catch-down growth are defined as height or weight growth above or below the statistical limits of normality for age [1,2]. Studies mostly conducted in developed countries have assessed the effects of intrauterine growth restriction (IUGR) and preterm (PT) birth on child growth, showing that many children achieve weight and height catch-up [3,4,5,6]. Studies assessing catch-down in children who suffered IUGR or were born PT are scarce [4]. Height catch-up is mostly observed between 6 and 12 months of life in children with IUGR[7,8] and between two and three years of age in PT children[8,9]. The phenomenon of catch-up allows PT newborns to reach growth equivalent to that of healthy children born at term during their first years of life [10]. In some children (10% to 15%) height catch-up does not occur and their height may not reach its full potential [8,11]
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