Secular change in height and weight of indigenous school children in Oaxaca, Mexico, between the 1970s and 2007

Thinness, overweight, and obesity in indigenous school children and youth in Mexico

Background: The prevalence of overweight (OWT) and obesity (OB), defined by the body mass index (BMI, kg/m²) among children and youth has increased worldwide in the last 30-40 years.Aim: To evaluate the weight status, defined by the BMI, of indigenous school children and youth resident in different regions of MexicoSubjects and methods: Students 6-18 years (31,448 boys, 27,306 girls) were enrolled in bilingual schools for indigenous children and youth in Mexico in 2012. Height and weight were measured; the BMI was calculated. The BMI of each student was classified relative to International Obesity Task Force (IOTF) age- and sex-specific criteria as thin (three grades), normal, overweight (OWT) or obese (OB). The sample was divided into five geographic regions for analysis: North, Central, South-Gulf, South-Pacific, and South-Southeast. Age- and sex-specific prevalence, 95% confidence intervals, and Chi-square tests were calculated.Results: Prevalence of OWT + OB was highest in the South-Gulf, South-Pacific and South-Southeast regions and lowest in the North and Central regions, while thinness was most prevalent in the North and Central regions.Conclusion: Prevalence of severe and moderate thinness was relatively low, while the combined prevalence of OWT + OB was generally more prevalent in indigenous boys than girls. However, the prevalence of thinness, OWT + OB among indigenous children and youth was lower than in the general population of children and youth in Mexico.

Geographic variation in the growth status of indigenous school children and youth in Mexico

OBJECTIVE

To analyze variation in the growth status of indigenous children and youth attending bilingual schools, escuelas albergues, for the indigenous population in México.

MATERIALS AND METHODS

The children and youth attended escuelas albergues in 1,009 localities in 21 Mexican states in 2012. Heights and weights of 31,448 boys and 27,306 girls 6-18 years of age were measured by trained staff at each school; the BMI was calculated. The students were divided into five geographic regions for analysis: North, Central, South-Gulf, South-Pacific, and South-Southeast. Growth status was compared to United States reference percentiles (P).

RESULTS

Mean heights of children and youth from the five regions varied between P10 and P5 of the reference until about 13 years (girls) and 14 years (boys); subsequently, heights were ≤P5. Mean weights in both sexes were at P25 of the reference between 6 and 12 years, and then varied between P25 and P10 in boys and were ≥P25 in girls. Given the elevated weights relative to heights compared to the reference, mean BMIs of indigenous boys and girls were at or above the reference medians. Children and youth in the North and Central regions were, on average, taller than those in the South-Pacific and South-Southeast regions, while heights of those in the South-Gulf region were generally intermediate. In contrast, mean weights and BMIs differed negligibly among the regions.

CONCLUSIONS

The geographic gradient in heights of indigenous children and youth was consistent with a north-to-south pattern noted among indigenous adults in studies spanning 1898 through 2013. Variation in height among children and youth likely reflected ethnic-specific and geographic variation interacting with economic and nutritional factors.

Postmenarche growth: cohort study among indigenous and non-indigenous Chilean adolescents

BACKGROUND

In Chile, indigenous and non-indigenous schoolchildren have the same stature when they begin school but indigenous adults are shorter, indicating the importance of analyzing growth during puberty. The aim of this study was to compare the growth of indigenous and non-indigenous girls during the 36 months after menarche in Chile's Araucanía Region.

METHODS

A concurrent cohort study was conducted to compare growth in the two ethnic groups, which were comprised of 114 indigenous and 126 non-indigenous girls who recently experienced menarche and were randomly selected. Height was measured at menarche and at 6, 12, 18, 24 and 36 months post-menarche. General linear models were used to analyze growth and a generalized estimating equation model was used to compare height at 36 months post-menarche.

RESULTS

At menarche, the Z-score of height/age was less for indigenous than non-indigenous girls (-0.01 vs. -0.61, p < 0.001). Indigenous girls grew at a slower rate than non-indigenous girls (6.5 vs. 7.2 cm, p = 0.02), and height at 36-months post-menarche reached -0.82 vs. -0.35 cm (p <0.001). In an adjusted model at 36 months post-menarche, indigenous girls were 1.6 cm shorter than non-indigenous girls (95% confidence interval: -3.13 to -0.04).

CONCLUSIONS

The height of indigenous girls at menarche was lower than that of non-indigenous girls and they subsequently grew less, maintaining the gap between the two groups. At the end of the follow-up period, the indigenous girls were shorter than their non-indigenous peers.

Altitude effects on growth of indigenous children in Oaxaca, Southern Mexico

The effect of altitude of residence on the growth status of 11,454 indigenous school children 6-14 years of age in Oaxaca, southern Mexico, was examined. Indicators of living conditions (human development index [HDI], index of community nutritional risk [INR], index of marginalization [IM], index of relative isolation [II]) were regressed on z-scores for height, weight and BMI, and the residuals were regressed on altitude of residence (km). Independent of other environmental conditions, altitude negatively affected height by approximately -0.07 z-scores per kilometer altitude above sea level. The estimated average decrease in stature was 0.92 cm per kilometer elevation. BMI was significantly increased, 1.2 units per kilometer elevation, consistent with earlier studies of growth status and altitude. In contrast, weight was not affected by altitude of residence. Approximately 36% of the reduction in height and 54% of the increase in BMI were due to altitude effects; the remaining changes in height and BMI were associated with environmental factors reflected in the indices of community well-being considered.