| Summary: | Introduction Ethnic differences in bone growth and proportions have previously been
investigated in relation to bone fragility. Differential growth in the axial and appendicular
skeletons has been suggested to predispose to differential susceptibility to fracture. The
developmental origins of bone size and osteoporosis have also been investigated. However, the impact of foetal programming on body proportions and limb lengths in unknown.
Objectives The aim of this study was to investigate the presence of ethnic and sex differences in axial and appendicular growth. Additionally, it was to investigate the impact of early life factors on skeletal dimensions and proportions in childhood .
Methods Anthropometric measurements of stature, weight, sitting height and limb lengths were taken on 368 black and white, male and female 9 year old children. DXA scans of the distal ulna;distal radius; hip and lumbar spine were also obtained. The same measurements were obtained for 197 of the black children who had birthweight and weight and length data at 1 year. For the first part of the analyses, Analyses of Covariance were performed to assess differences in limb lengths adjusted for differences in stature. Multiple regression analyses were used to assess significant predictors of site-specific bone mass. Comparisons were made after adjustment for weight, weight and stature and weight and regional segment lengths. For the second part of the analyses, Analyses of Covariance were performed to assess differences in stature and regional
segment lengths at different tertiles of birthweight, and weight and height at 1 year. Stepwise multiple regressions were performed with early life growth patterns to assess significant predictors of stature and regional segment lengths at 10 years.
Results Black children had longer limbs but shorter trunks than white children. Regional
segment length were a more significant predictor of site-specific bone mass than stature. In black boys birthweight had positive but weak associations with stature and regional segment length while in girls the association were marginal. In contrast, weight and height at 1yr had strong associations with stature and regional segment lengths.
Conclusion There is a differential effect of ethnicity and sex on the growth of the axial and
appendicular skeletons, and regional segment length is a better predictor of site-specific bone mass than stature. Early life growth has a long-term influence on stature, as well as on regional segment lengths but marginal effect on body proportions.
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