ABSTRACT
The longitudinal growth of an individual child is a dynamic statement of the general health of that child. Measurements should be performed often and accurately to detect alterations from physiologic growth. Although any single point on the growth chart is not very informative, when several growth points are plotted over time, it should become apparent whether that individual's growth is average, a variant of the norm, or pathologic. Somatic growth and maturation are influenced by several factors that act independently or in concert to modify an individual's genetic growth potential. Linear growth within the first 2 y of life generally decelerates but then remains relatively constant throughout childhood until the onset of the pubertal growth spurt. Because of the wide variation among individuals in the timing of the pubertal growth spurt, there is a wide range of physiologic variations in normal growth. Nutritional status and heavy exercise training are only 2 of the major influences on the linear growth of children. In the United States, nutritional deficits result from self-induced restriction of energy intake. That single factor, added to the marked energy expenditure of training and competition for some sports, and in concert with the self-selection of certain body types, makes it difficult to identify the individual factors responsible for the slow linear growth of some adolescent athletes, for example, those who partake in gymnastics, dance, or wrestling.
INTRODUCTION
A child's growth can be compared with that of his or her peers by referring to the norm on an appropriate growth chart. More important, the longitudinal measurements of a child's growth are a dynamic statement of his or her general condition or health.
Tanner [1] has proposed that children be measured accurately to identify individuals or groups of individuals within a community who require special care, to identify illnesses that influence growth, or to determine an ill child's response to therapy. The linear growth of a child-adolescent athlete may also reflect the adequacy of energy intake for a particular training regimen. Measurement of growth may also be used as an index of the general health and nutrition of a population or subpopulation of children.
By definition, normal [physiologic] growth encompasses the 95% CI for a specific population. Most children and adolescents who have a normal growth pattern but who remain below the lower 2.5 percentile [approximately −2.0 SD] are otherwise normal. The farther an individual's growth falls below the −2.0 SD mark, the more likely he or she is to have a condition that is keeping him or her from reaching the genetically determined height potential.
Cross-sectional data are derived from the measurements of many children at various ages and are generally used to derive standard growth charts. However, individual children do not necessarily grow according to these standard curves. Longitudinal growth charts derived from growth points of the same child over time more accurately describe the growth pattern of an individual. In adolescence, there may be quite large deviations from the derived percentile lines, depending on the timing and tempo of the pubertal growth spurt. An average pubertal growth pattern is built into the percentiles derived from cross-sectional data, but virtually no one individual adheres strictly to that pattern.
GROWTH MEASUREMENTS
The growth of children should be measured periodically and accurately. Two common devices are adequate for such measurements and were described by Rogol and Lawton [2].
Neonates and infants
Small inaccuracies in length measurement can easily affect a child's percentiles on growth curve charts. Infants should be placed with the top of the head against the fixed headboard of the measurement device and with the eye-ear plane perpendicular to the base of the device [Figure 1]. The child's knees must be flat against the table and the footboard moved until the soles of the feet are against it, with the toes pointing up.
FIGURE 1.
Growth measurement length of an infant. Reprinted with permission from reference 2.
Children and adolescents
Growth in children older than 2 y is measured with the child standing. A diurnal variation of