Have Socio-Economic Disparities in Growth Trajectories Changed Among Chinese Children and Adolescents in Recent Decades?

Abstract

Backgrounds: Socio-economic disparities in growth trajectories of children from low-/middle-income countries are not well-understood, especially those experiencing rapid economic growth. We investigated socio-economic disparities in child growth in recent decades in China. Methods: Using the longitudinal data of 5,118 children/adolescents (7-18y) from the China Health and Nutrition Survey between 1991-2015, we estimated mean height and BMI trajectories by socio-economic position (SEP) for each cohort (born in 1981-95, 1986-90, 1991-95, 1996-2000) and sex using random-effects models. We also estimated differences between high (urbanization index ≥median, household income per capita ≥median, parental education ≥high school, or occupational classes I-IV) and low SEP groups. Findings: Mean height and BMI trajectories have shifted upwards across cohorts. In all cohorts, growth trajectories for high SEP groups were above those for low SEP groups across SEP indicators. For height, socio-economic differences persisted across cohorts (e.g. 3.8cm and 2.9cm in the earliest and latest cohorts by urbanization index for boys at 10y, and 3.6cm and 3.1cm respectively by household income). For BMI, socio-economic differences increased across cohorts as the trend was faster in high than low SEP groups (e.g. from 0.5 to 0.8kg/m2 by urbanization index, and 0.4 to 1.1kg/m2 by household income for boys at 10y). Similar trends were found for stunting and overweight/obesity by SEP. There was no association between SEP indicators and thinness. Interpretation: Socio-economic disparities in physical growth exist among Chinese youths. Short stature was associated with lower SEP, whereas high BMI was associated with higher SEP. Inequalities in childhood BMI widened while large inequalities in height persisted between 1991-2015. Funding Information: UCL Overseas Research Scholarship and China Scholarship Council (MG); UK Medical Research Council New Investigator Research Grant (MR/P023347/1) (WJ). Declaration of Interests: None declared. Ethics Approval Statement: All participants provided written informed consent. The University of North Carolina and the Chinese Centre for Disease Control and Prevention reviewed and approved the data collection procedures.