## Definition

There is not one, but several growth curves, which allow a child's body to develop in a normal and controlled fashion. Measurements are taken on a regular basis, from birth until the end of puberty. There are three types of growth curves: the height curve, the weight curve, and the cranial diameter curve. A fourth type studies the Body Mass Index, or BMI, based on the relation between weight and height. On each curve there are several further curves for which a percentage is indicated, representing percentiles. The percentiles correspond to the percentages of children in the same age group whose values are situated below the curve; this means that a child whose height is situated below the 50th percentile curve is part of the half consisting of the shorter children. Curves are different for boys and for girls, and the study of a child's curve must be in relation to the study of the other curves: a child whose height is less than the 10th percentile but whose weight is greater than the 90th percentile is overweight, hence the importance of the BMI curve.