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Patterns of linear growth in rural Guatemalan adolescents and children(¹,²)

REYNALDO MARTORREL*³ DIRK G. SCHROEDER,* JUAN A. RIVERA† AND HALEY J. KAPLOWITZ‡

*Department of International Health, The Rollins School of Public Health of Emory University, Atlanta, CA 30322, †Centro de Investigaciones en Salud Pública, Instituto Nacional de Salud Pública 62508 Cuernavaca, Morelos, México, ‡Genentech, Inc., South San Francisco, CA 94080

¹ Published as a supplement to The Journal of Nutrition. Guest editors for this supplemental publication were Reynaldo Martorell, The Rollins School of Public Health of Emory University, Atlanta, GA, and Nevin Scrimshaw, The United Nations University, Boston, MA.

² Data collection and analyses were supported by NIH grant HD22440 and by the International Center for Research on Women (ICRW), Contract # IC-75/03.

³ To whom correspondence should be sent: Department of International Health, The Rollins School of Public Health of Emory University, 1518 Clifton Road, N.E., Atlanta, GA 30322.

Materials and methods
Results
Discussion
Literature cited

While much is known in developing countries about growth in early childhood and the factors that shape its course, knowledge about growth during later childhood and adolescence is limited. Research to date indicates that growth failure and nutritional stress in poor children from developing countries are greatest in the first 2-3 y of life (Beaton et al. 1990). Growth during later childhood and adolescence in these same societies appears to be considerably less constrained, if at all (Martorell et al. 1994). Some argue that adolescence is a time when the growth retardation produced in early childhood may be recuperated (Delgado et al. 1987). However, the research to support the claim that catch-up growth can occur to a significant degree during adolescence is weak (Martorell et al. 1994). The objective of this paper is to compare patterns of growth of poor Guatemalans during childhood and adolescence to both a racially similar population of Mexican Americans and a general USA reference. Several key questions guide the analyses: what are the periods in life in rural Guatemala when significant growth failure occurs? Specifically, is adolescence a time of constrained growth or instead, is it a period when some of the growth failure of earlier childhood is overcome by compensatory growth?

Materials and methods

The subjects included in this study were participants of a longitudinal study conducted by the Institute of Nutrition of Central America and Panama (INCAP) in four villages of eastern Guatemala. The study took place between 1969 and 1977 in four Ladino (i.e., Spanish speaking, mixed Spanish/Amerindian population) villages. The objectives of the study were to test the effects of improved nutrition achieved through food supplementation on physical growth and mental development. The groups under intensive monitoring were pregnant and lactating women and all children seven years of age and less. Details about the methods of this longitudinal study are found elsewhere (Martorell et al. 1995). Briefly, weight was measured on a beam scale to the nearest 10 g with children wearing a light shift, the weight of which was later subtracted. Supine lengths were measured using a standard measuring table to the nearest 0.1 cm; no standing heights were taken on children <7 y of age.

In 1988-89, a cross-sectional, follow-up study was carried out which included data on height and other measures of linear growth, weight, frame size, circumferences and skinfold thicknesses (Martorell et al.1995). This article emphasizes the height and weight data. Standard measurement techniques were used (Lohman et al. 1988). Weight was measured to the nearest 100 g using a beam balance scale (Health O Meter). Subjects were given a light shift to wear and shoes were removed. A portable anthropometer in freestanding mode was used to measure height to the nearest 0.1 cm. The body mass index (BMI) was estimated as weight (kilograms) over height squared (meters²).

The anthropometric data are compared with three reference populations. The first is the United States National Center for Health Statistics/World Health Organization (NCHS/WHO) reference, which is widely used by researchers throughout the world (WHO, 1983). For length data from birth to 36 mo this reference is based on data collected from children from the Fels Research Institute's (Ohio) longitudinal study of 867 white, middle-class children (Dibley et al. 1987a, Hamill et al. 1979) Height data from 2 to 18 y are from national surveys carried out by NCHS. The appropriateness of these data as a reference (Dibley et al. 1987b) and their comparison with other references are discussed elsewhere (Stephenson et al. 1983).

For adolescents and young adults, a reference based on the first (1971 -74) and second (1976-80) National Health and Nutrition Examination Survey (NHANES) published by Frisancho (1990) is used. The NHANES surveys included representative samples of subjects in the United States and as such, reflected the ethnic diversity of the country in the 1970s. For the most part, however, subjects included in these surveys were of European origin; in the combined data set used by Frisancho, 78% of subjects were Caucasian (Frisancho 1990). The reasons for using Frisancho's (1990) reference data for comparison are that percentile values are provided for adults and that additional anthropometric variables (e.g., BMI) are presented. For ages presented in both the Frisancho and NCHS/WHO references, values are very similar. This similarity is not unexpected because both include a common data source, NHANES I; also, average stature did not differ in NHANES I and II. The reason for not using only the NCHS/WHO (WHO 1983) curves is that they do not provide data after age 18 y or for variables other than height and weight. A disadvantage of Frisancho's curves is that the data were not smoothed and this may lead to some irregularity.

A reference population of similar ancestry as the study population is also used for comparison. The reference population selected for this purpose is that of Mexican-Americans measured in the Hispanic HANES of 1982-84 (Najjar and Kuczmarski 1989). Although poverty may have constrained growth, Mexican-Americans are undoubtedly much better off than rural Guatemalans. In fact, the growth patterns of Mexican-Americans are strikingly similar to those of well-todo samples from the cities of Mexico and Guatemala (Johnston et al. 1973, Johnston et al. 1976, Martorell et al. 1989, Ramos-Galvan 1975).

Subjects from all four villages included in the original study are pooled in the analysis because the purpose is to describe general differences in linear growth with respect to the reference populations selected. Differences between Guatemalans and the reference populations are overwhelmingly larger than intervillage differences (see Rivera et al. 1995 for examination of these differences). For the later ages, the study also combines, for the same reason, migrants and nonmigrants (Martorell et al.1995). The follow-up study was able to collect data on 73% of former participants; coverage was greater for village residents (89%) than for migrants (41 %).

For the analyses of child growth, data on 1232 boys and 1160 girls are included in this paper. Because of the longitudinal nature of the earlier study, individual subjects may be represented at more than one age interval.

In 1988-89, the subjects ranged from 11 to 27 y of age (born between 1962 and 1977). Presented in this paper are data for 786 males and 719 females 11.024.9 y in age; subjects 25-27 y are excluded to conform with the Frisancho's age groupings (1990), which were yearly to 17 y (e.g., 17.0- 17.9), and at longer intervals thereafter (i.e., 18.0-24.9 y, for which we have subjects in the entire age range; 25.0-29.9 y, for which we lack subjects 28-29.9 y).

Mean and median values by age and sex are given in tabular form in this paper only for the rural Guatemalan sample. Medians for Guatemalan and Mexican-American samples are plotted relative to the percentile distribution in the USA reference population. Results of formal statistical tests are not presented because the differences of interest in this study are extremely large and often statistically significant. Rather, readers are encouraged to assess the magnitude of differences relative to the percentile distribution.

TABLE 1 Length or height¹ (cm) of Guatemala children. adolescents and young, adults

¹ Supine length was measured until 7 y of age; l cm was subtracted from length values in children >24 mo to approximate height values used in the reference population. Standing height was measured at 11-25 y. Measurement before age 7 y was at exact ages.

² Measured at 15 days of life.

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