Growth of height and leg length of children in Beijing and Xilinhot, China

摘要

A number of papers on the growth of Chinese children have been published in local journals in China in the Chinese language. However, we noticed that height and weight are the main focus of these studies. Because leg length relative to height is of interest in human biology, the current study focuses on the growth of this proportion. Two groups of Chinese children were investigated: 587 boys and 625 girls in Beijing in 1997 aged 6–18 years, and 579 boys and 615 girls in Xilinhot, Inner Mongolia, in 2005 aged 7–18 years. Height and leg length (iliospinal height) were measured, and the ratio of leg length to height was calculated for each child. Mean distance curves and spline-smoothed yearly increment curves were obtained. In order to clarify the difference between the two groups of Chinese children, data from Japanese children were adopted as a control. The Beijing children were taller than the Xilinhot children, but no difference was detected in leg length between them. The ages at ‘take-off’ and ‘peak’ obtained on the yearly increment spline-smoothed curve of height in the Xilinhot children boys were 1.2–1.8 years earlier, respectively, than those of the Beijing boys. In the girls, these two ages were almost the same in the two cities, although the ‘peak’ was 1.8 cm greater in the Xilinhot girls. Leg length in the boys was almost the same in both Beijing and Xilinhot. In the girls of the Xilinhot group, leg length was greater after puberty. Consequently, the ratio of leg length to height was greater in the Xilinhot children than the Beijing children. It is suggested, in China, that socioeconomic factors influence growth of height to a greater extent than growth of leg length, and that leg length and leg length relative to height might be controlled by a genetic factor.