Growth is not uniform from infancy to adulthood, it occurs in patterns that occur at different ages and vary in magnitude among children. The patterns of growth of a child or a group of children can be described mathematically through models that summarize the overall pattern of growth across an age range. Knowledge of these patterns is necessary to interpret previous changes in individuals and they are the basis of informed expectations of future changes. This knowledge is fundamental to understanding the mechanisms that influence growth and maturation and the consequences of unusual changes. Considerable information is available about patterns of change in the common growth measures, but knowledge is sparse for patterns of change in total body composition, particularly for infants. This chapter describes normal growth patterns and discusses spurts, increments, diurnal and seasonal variations, tracking, decanalization, failure-to-thrive, catch-up growth, adult stature prediction and target stature. First, the utility of several mathematical models that can be used to describe growth patterns is presented including the subsequent analysis of their parameters.

MATHEMATICAL MODELS FOR DESCRIBING GROWTH PATTERNS

The procedure for describing patterns of change in growth variables begins by developing a model that describes and summarizes the changes in the variable across age (Guo et al., 1997a, 2000a). The selection of a model begins with examination of the patterns of change reported in the literature.