Measurement of growth variability and environmental quality in Guatemalan children

The measurement of within-population growth variability may be a sensitive indicator of environmental quality. Specifically, it is hypothesized that within-population variability will increase in adverse environments. To evaluate this hypothesis the variability in stature growth of three samples of Guatemala school children (5-10 years old) is assessed. These samples include high socioeconomic status (SES) ladinos (84 boys and 98 girls) and low SES ladinos (136 boys and 101 girls) living in Guatemala City and very low SES Mayan Indians (139 boys and 73 girls) living in a rural town near the city. SES is used as a proxy for environmental quality. The coefficient of variation (CV) for distance achieved at each age, or for the increment of growth from age to age, is used as the measure of variability. The three samples differ significantly for variability in stature growth, both for the distance and the increments of growth. Low SES urban ladinos have the largest variability. Very low SES Mayan children have coefficients of variation that are sometimes equal to, and sometimes either larger or smaller than, CVs for the high SES ladinos. The results show that degree of environmental adversity does not correlate uniformly with growth variability. Factors such as rates of infant and early childhood mortality and the greater heterogeneity of the low SES urban environment, compared with the high SES urban or low SES rural environments, may account for differences in the CV in these three samples.