Background Globally, 80% of cardiovascular diseases (CVD) occur in low- and middle-income countries. Many CVD risk factors have their origins in early-life. We investigated (1) how growth trajectories from childhood to late-adolescence and socio-economic disparities in growth have changed in China; (2) how childhood BMI trajectories were associated with CVD risk factors in early to mid-adulthood.

Methods Using the longitudinal data in children and adults from the China Health and Nutrition Survey between 1991–2015 (9 waves), we estimated mean growth trajectories (7–18 years, n=~4000) for cohorts born in 1981–85, 1986–90, 1991–95, 1996–2000 using random effect models. We compared growth trajectories by socio-economic position(SEP) in childhood and by CVD risk factors in adulthood (20–45 y).

Results Growth trajectories shifted towards higher BMI and taller stature across cohorts. The overall increments were greater in height than in BMI: by 0.20 (95% CI: 0.17–0.23) vs 0.11 (0.08–0.13) in z-scores for each successive cohort. Mean BMI and height trajectories for high SEP groups were above those for low SEP groups across SEP indicators (i.e. levels of urbanisation, household income, parental education and occupational class). For height, socio-economic differences persisted across cohorts (e.g. for boys at 10 years, 3.8 cm in earliest and 2.9 cm in latest cohort by urbanization index, and 3.6 cm and 3.1 cm respectively by household income). For BMI, the trends were greater in high than low SEP groups, thus socio-economic differences increased across cohorts (e.g. 0.5–0.8 kg/m2 by urbanization index, 0.4–1.1 kg/m2 by household income for boys). BMI trajectories in childhood and adolescence were associated with CVD risk factors in adulthood. Mean childhood and adolescence BMI was higher for those with central obesity (boys:1 kg/m2, girls:0.5 kg/m2), alleviated BP (~0.5 kg/m2), dyslipidemia (boys:~0.5–1 kg/m2,girls:<0.5 kg/m2), compared to those without. For those with diabetes, mean BMI was higher in childhood (not from adolescence).

Discussion Using a longitudinal survey spanning over 24 y, and a range indicators for childhood SEP/adult CVD, we found that BMI and height trajectories have shifted upwards in Chinese children during 1991–2015. However, socio-economic disparities in growth persisted (widened in BMI), with short stature being associated with lower SEP, but high BMI with higher SEP. High BMI in childhood/adolescence were associated with adult CVD risk factors.