Association of maternal short stature with stunting in Mexican children:: common genes vs common environment

Objective: To evaluate the association between stunting in children and maternal short stature, controlling for potential environmental confounders. Design: 1988 Mexico National Nutrition Survey. Setting: Mexico. Subjects: The final sample size was 4663 pairs of children (< 5 y) and their mothers (12-49 y) from a total of 13 236 surveyed houses. Main outcome measures: Stunting (height-for-age Z-scores < -2). Results: The prevalence of stunting in children was 19%, and 10% of the mothers exhibited short stature (< 145 cm). In the crude analysis, mothers with short stature were significantly more likely to have stunted children (odds ratio (OR) = 4.0; 95% confidence interval (CI) = 3.2-4.8; P-value < 0.001). In a multiple logistic regression model the OR for child stunting was reduced, but remained significant OR = 2.0; 95% CI = 1.6-2.6; P-value < 0.001) after adjustment for region, urban/rural residence, socio-economic status, household size, child age and presence of infection in the past 14 d, and maternal age, body mass index (BMI), and educational level. Adjusted ORs varied between regions Mexico City, OR = 3.9; North Mexico, OR = 3.1, Central Mexico, OR = 2.0; South Mexico, OR = 1.6. Comparison of crude vs adjusted estimates pointed to regional differences in the proportion of association between maternal and child short statures explained by environmental determinants. Conclusions: Maternal stature, reflecting her potential height and early environment, appeared to contribute to child height independently of the shared risk factors that could affect stature. Nonetheless, we could explain much of the association between stunting in children and maternal short stature by environmental factors, and part of the residual variability may be due to unmeasured determinants. Regional differences pointed to a predominance of environmental factors in explaining child stunting in poorer regions.