Socioeconomic disparities in growth trajectories of Chinese children and adolescents during 1991-2015

Abstract

Abstract Backgrounds Socioeconomic (SEP) disparities in growth of children from low-/middle-income countries are not well understood, especially in countries experiencing rapid economic growth. We investigated how SEP disparities in child growth in China have changed over time. Methods Using the longitudinal data of 5,118 children and adolescents (7-18y) from China Health and Nutrition Survey (10 sweeps, 1991-2015), we derived four cohorts born in 1981-95, 1986-90, 1991-95, 1996-2000. We applied random-effects fractional polynomial models to estimate mean height and BMI trajectories for each gender separately, by socioeconomic position (SEP) for each cohort. SEP disparities were estimated as differences between high and low SEP groups (by community-level urbanization index, household income/capita, parental education, and occupational class). We also examined whether SEP disparities in nutritional status (stunting, thinness, overweight/obesity) have changed over time. Results Mean height and BMI increased across cohorts, with differences being greatest in adolescence. The increasing trend for height was similar in high and low SEP groups, thus positive SEP differences in mean height persisted across cohorts (e.g. for boys at 10y, were 3.8cm in the earliest and 2.9cm latest cohorts at by urbanization index, and were 3.6cm and 3.1cm by HH income). For BMI, the increasing trend was much faster in high (vs low) SEP groups, thus SEP differences in mean BMI increased across cohorts (e.g. for boys at 10y, increased from 0.5 to 0.8kg/m2 by urbanization index, and 0.4 to 1.1kg/m2 by HH income). Findings for stunting and overweight/obesity were consistent with those for height and BMI. No significant association was found between SEP and thinness. Conclusions Short stature is associated with lower SEP, whereas high BMI is associated with higher SEP among Chinese youths. Between 1991-2015 in China, inequalities in childhood BMI increased while those for height remained fairly constant. Key messages Short stature is associated with lower SEP, whereas high BMI is associated with higher SEP among Chinese youths. Between 1991-2015 in China, inequalities in childhood BMI increased while those for height remained fairly constant.