Reference charts of sitting height, leg length and body proportions for Chinese children aged 0-18 years

Background: The reference charts of sitting height (SH), subischial leg length (LL) and the sitting height/leg length ratio (SH/LL) are useful tools in assessing body proportion for clinicians and researchers in related areas. However, reference charts of body proportions for Chinese children and adolescents are limited. Aim: To construct reference charts of SH, LL and SH/LL for Chinese children and adolescents. Subjects and methods: Stature and sitting height of 92 494 (46 240 boys and 46 254 girls) healthy Han nationality children, aged 0-18 years, were measured in two national large-scale cross-sectional surveys in 2005 in China. SH/LL was selected as the indicator of body proportion. References of SH, LL and SH/LL were constructed using the LMS method. Results: The reference charts demonstrated that SH and LL increased with age. Growth in SH slowed by the age of 17 years in boys and 15 years in girls. Similarly, growth in LL slowed at 16 years in boys and 14 years in girls. The SH/LL ratio declined from birth (2.00 in boys and 2.03 in girls) to 13 years in boys (1.11) and to 11 years in girls (1.13), then increased slightly to the age of 18 (1.16 in boys and 1.18 in girls). The gender difference of SH/LL was not significantly different before the age of 11 years. After the age of 11, SH/LL appeared elevated in girls compared to boys. Conclusions: The reference charts of SH, LL and SH/LL are useful tools for assessing body proportions for Chinese children and adolescent individuals.