The association between urbanization and child height: a multilevel study in China

BACKGROUND: Recent economic development in China has been accompanied by well-documented health inequalities between regions. The impact of individual factors on child height has been widely studied, but the influence of community-level factors has not yet been fully studied. METHODS: The cross-sectional data of 1606 Chinese children aged 5–18 years from the China Health and Nutrition Survey 2011 were used. Multilevel analysis was used to examine the association of community factors (using urbanization index) with child height. Child height was measured following standardized procedures, and height-for-age Z scores were calculated as outcome variables. Datasets were presented at two levels: community variable (Level-2) was an urbanization index which is a composite score summarizing 12 community-level contextual factors. Individual variables (Level-1) were child gender, ethnicity, percentage of energy intake from protein, maternal height, maternal education level, and family income. RESULTS: Urbanization index was associated with child height. Among the 12 community-level factors, ‘education’ were positively associated with child height. Additionally, stratified analyses by age showed that ‘population density’ and ‘housing’ were positively significantly associated with the height of elder children (13–18 years). At the individual level, male sex, higher maternal height, higher maternal education levels, higher family income, and higher percentage of energy intake from protein, were significantly positively associated with child height. CONCLUSIONS: Our findings point to the role of contextual factors that generate differences between regions in shaping the distribution of child physical health outcomes. Our study suggests that public health programs and policies for child’s physical development may need to combine individual-centered strategies and also approaches aimed at changing residential environments.