Longitudinal analysis of adolescent growth of ladino and Mayan school children in Guatemala: effects of environment and sex.

The rate of growth in height and the timing of adolescent growth events are analyzed for two samples of Guatemalan children. One sample includes Mayan school children, 33 boys and 12 girls between the ages of 5.00 to 17.99 years, living under poor conditions for growth and development. The second sample includes ladino children, 78 boys and 85 girls of the same age range, living under favorable conditions for growth. The Preece-Baines model I function is used to estimate mean values for rates and timing of childhood and adolescent growth events for the two groups. Significant statistical contrasts (t-tests) of these means show Mayan boys reach the age of "take-off" (TO; the onset of the adolescent growth spurt) 1.45 years later, achieve peak height velocity (PHV) 1.68 years later, and continue growing for about 2.0 years longer than do the ladino boys. Despite the Mayan boys' increased duration for growth they grow significantly more slowly than the ladinos. Mayan boys are 6.60 cm shorter than ladinos at the age of TO and are estimated to be 7.71 cm shorter than the ladinos at adulthood. Mayan girls reach the age of TO 0.93 years later than do the ladina girls, but the two groups do not differ in the age at PHV or the age at adulthood. The mean height of Mayan girls is significantly less than that of ladinas at the age of TO (6.5 cm), and this difference increases to an estimated 11.14 cm at adulthood. Possible causes of these ethnic and sex-related differences in amounts and rates of growth are discussed in relation to hypotheses about the genetic and environmental determinants of human development.

Interaction of nutritional and socioeconomic status as determinants of cognitive development in disadvantaged urban Guatemalan children.

The relationship between nutritional status, measured by height for age, and cognition, measured by WISC full-scale IQ, was studied in a longitudinal sample of 459 urban Guatemalan children, aged 4-9 years, from a disadvantage community of the fringe of Guatemala City, examined annually over a 3 year period. Socioeconomic status (SES) was controlled by developing a composite index for each home. The mean IQ differed significantly from the lowest to the highest quartiles of stature, the difference between the two extreme quartiles being approximately 0.3 SD of IQ. There was a significant interaction between SES and stature in their effects on IQ. Whereas nutritional status and SES affected IQ in an additive fashion in the upper three SES quartiles, there was no difference in IQ attributible to stature among children from the most disadvantaged homes. This analysis indicates that the mild-to-moderate protein-energy malnutrition (defined by height for age) that is prevalent among children from disadvantaged environments in developing countries is significantly related to cognitive development. However, in the poorest homes, SES is seen as a more important determinant of cognitive development than stature.

Growth status, age, and grade as predictors of school continuation for Guatemalan Indian children.

Schooling is considered by many researchers and agencies as an important contributor to individual and national development for populations living in the less developed countries. Accordingly, programs to increase school enrollment and continuation from grade to grade are being developed for many of these countries. This paper investigates the relationship of physical growth status (height, weight, and body composition), grade in school, and age to school continuation for a sample of Indian children living in a village near Guatemala City. It was found that physical growth status, a reflection of health and nutritional status, does not predict school continuation. A child's age and current grade in school do predict continuation. Most children leave school after reaching 9 years of age or after completing the second grade. It is suggested that children may learn enough to satisfy their parents' expectations by this age or grade. Also, the child's economic value to his or her family may be a significant reason for school drop-out.

Growth status of disadvantaged urban Guatemalan children of a resettled community.

This paper reports the physical growth and body composition from the first year of longitudinal study of 519 Guatemalan children, and their families, from a disadvantaged urban community consisting largely of refugees of the 1976 earthquake. Four cohorts are described, composed of children of 1,3,5, and 7 years at examination. The children are smaller, weigh less, and have reduced fat stores compared either to NCHS reference data or to upper SES Guatemalan children. Stature (or length) and head circumference deviate more from reference data than do triceps or upper arm muscle circumference. Greater deviations are found in the linear dimensions of males than of females. These children are the smallest yet described from Guatemala City, though they are slightly larger than available rural samples. This suggests a continuum of environmental effects acting upon the growth of children of differing socioeconomic levels.

The relationship of socioeconomic status and sex to body size, skeletal maturation, and cognitive status of Guatemala City schoolchildren.

Longitudinal data from a study of child development in Guatemala City were used to describe the influence of socioeconomic status and sex on physical and cognitive growth status. The correlation between the growth status variables was also analyzed. The sample included 144 Guatemalan children, 46 of low SES, 52 of middle SES, and 46 of high SES. The children were students in 5 urban primary schools. 3 physical variables, height, weight, and skeletal age, were measured annually from first to sixth grade. Two cognitive variables, general intelligence and reading ability, were measured in grades 1, 3, 4, or 5. Significant differences between SES groups existed for all variables. However, the differences in each grade were greater for the cognitive measures than for the physical measures. Compared with high SES children, middle SES boys and low SES boys and girls experienced significantly greater delayed growth in height than in weight or skeletal age. It is possible that these height delays may result in a permanent reduction in stature. The only consistently significant sex-related difference was for skeletal age; girls were more mature than boys in each grade. When SES was statistically controlled, there was no significant correlation between physical and cognitive growth status for girls and only a few moderate but statistically significant correlations for boys.

Ethnic and secular influences on the size and maturity of seven year old children living in Guatemala City.

Three groups of children, those of European parentage, those of Guatemalan parentage, and those of mixed European-Guatemalan parentage were measured for height, weight, and skeletal maturity. The children were born between 1945 and 1965, they were all of high socioeconomic status, and they all attended the same private school in Guatemala City. At 7 years, the boys of the European group were significantly taller than boys of the Guatemalan group. European and mixed European-Guatemalan girls were significantly taller than Guatemalan girls. These results are maturity independent. The influence of skeletal age was removed statistically by analysis of covariance. Girls of the mixed group were significantly heavier than girls of European and Guatemalan groups. Mixed group girls also had more significantly advanced skeletal ages than European girls. When the patterns of size and maturity status are analyzed by sex, there is evidence for a relatively greater environmental influence on the boys and a relatively greater genetic influence on the girls. Dividing the data into two birth year cohorts, 1945 to 1955, and 1956 to 1965, does not provide evidence for secular trends in growth or maturation. These results are similar to those from studies in developed nations that report an end to the secular trend for the "well off" population of those countries.

Biosocial effects of urban migration on the development of families and children in Guatemala.

The relationship between rural to urban migration and child growth and family structure is reported in sample of 302 children from families of low socioeconomic status, living in Guatemala City. The sample was divided into three groups: 1) children of parents born outside the city, 2) children of parents born in the city, and 3) children with one migrant and one city-born parent. Children of migrants to the city were the smallest and significantly shorter than children of migrant city-born parents. Migrant parents also had the largest families; family size correlated negatively with growth in height. Growth in weight followed a pattern similar to height, but no significant differences associated with migration status were found between groups.

Body composition and nutritional status of urban Guatemalan children of high and low socioeconomic class.

The effects of socioeconomic differences on the nutritional status of two groups of urban living children are considered via an anthropometric assessment of body composition. The sample consists of 981 Guatemala City children, 7.00 to 13.99 years old. Of high and low socioeconomic status (SES). High SES children have larger median values for triceps skinfold, subscapular skinfold, arm circumference, and estimated mid-arm muscle and fat areas than low SES children. Compared with children of a US reference sample, the high SES children generally have larger values for all variables and the low SES children have smaller values. However, the differences between the low SES children and the children of the other two samples are greater for arm fat area than for arm muscle area. The analysis suggests that low SES Guatemalan children suffer to a greater extent from chronic energy, rather than protein, undernutrition. A similar pattern of energy malnutrition has been observed for rural Guatemalan children. These combined data suggest that estimates of fat reserves of the arm provide a useful indication of nutritional status for Third-World children. Results from rural Costa Rican and Honduran studies have been taken to mean that muscle reserves are better than fat reserves as indicators of nutritional status in developing countries. But, those studies did not estimate cross-sectional muscle and fat areas and only considered the extremes of the population distribution for muscle and fat.