Numerical assessment of a child's physical growth in relation to statistical average.

Using statistical data, the American Academy of Pediatrics and the National Institutes of Health in the United States have developed tables to illustrate the growth patterns of children. These tables describe the population of all children of a certain age, with ranges for weight, height, and other physical characteristics. For most children, anatomical age—based on weight and height measurements—is the same as chronological age—based on the number of months or years since birth. However, when a child's physical growth falls outside the range of his chronological age, the child's age will be determined by his growth. For example, if a six-yearold's height and weight falls within the range for five-year-olds, his anatomical age will be given as five.