Secular Change in Body Proportions of Macao Children and Adolescents Aged 3–19 Years Across Four Surveys, 2005–2020

OBJECTIVES: To describe how the secular stature gain was divided between sitting height and leg length across survey intervals and ages, and whether the age at the sitting-height ratio minimum changed. METHODS: We designed and conducted four rounds (2005-2020) of the Macao Citizens Physical Fitness Monitoring Survey, a stratified cluster sample of kindergartens and schools, and analyzed 21 919 records of residents aged 3-19 years. Changes were adjusted for age and sex, with standard errors clustered on institution; the age at the ratio minimum was located on penalized-spline curves, with cluster-bootstrap intervals. RESULTS: Height was 1.97 cm (95% confidence interval [CI] 1.48-2.47) greater in 2020 than in 2005: leg length 0.91 cm (0.66-1.15) and sitting height 1.06 cm (0.77-1.36). Between 2005 and 2010 both segments increased, leg length by more (0.63 cm) than sitting height (0.30 cm), and the ratio fell 0.13 percentage points (-0.19, -0.06); between 2015 and 2020 sitting height rose 0.46 cm, leg length showed no statistically detectable change (0.04 cm; -0.22, 0.30), and the ratio rose 0.13 percentage points (0.04-0.22). Gains were largest at 10-14 years. The age at the ratio minimum did not change detectably (2015 vs. 2005: boys -0.30 years, -0.70 to 0.27; girls -0.93 years, -1.92 to 0.08). CONCLUSIONS: Across successive survey populations, the stature gain came mainly from the legs in the earliest interval and from sitting height in the latest, without a detectable change in the age at the ratio minimum.