Contribution of growth phases to adult size

Based on the data of the First Zurich Longitudinal Growth Study we investigate how interindividual differences in adult size arise in the variables leg height, sitting height and standing height, arm length, bi-iliac width and bihumeral width. Specifically, we are also interested in the question of whether across sexes and variables the same growth phases and the same parameters are predictive for achieving a certain adult size. A rather complex pattern emerges, demonstrating that regulation of growth is not the same for boys and girls and moreover is not the same for the six anthropometric variables studied. Prepubertal growth is characterized by its intensity (average velocity) and by its duration. Whereas duration has by itself no appreciable influence on adult size, prepubertal intensity determines adult size to a high degree across all variables and both sexes. The intensity of prepubertal growth determines adult size to a larger degree for boys than for girls. For a given size at the end of the prepubertal period, a small duration enhances the chance of obtaining a large adult size. Compared with prepubertal growth, the amount of variance of adult size explained is small for pubertal parameters, and--with respect to linear measures--significant for girls only. A small duration of prepubertal growth is in the following mainly compensated by a stronger pubertal spurt (PS), to a varying degree across variables. The overall picture which emerges indicates that sitting height--and to a lesser extent bihumeral width--develop in a more irregular fashion than the variables bi-iliac width and leg height.