Physical Growth

Physical growth and maturation are often used as indicators of child health because they are sensitive to nutritional deficiencies, infection, and poverty. Growth is a very adaptable process that will slow in the face of extreme nutritional deficiency, for example, as a mechanism to conserve nutrients for body functions essential to the child's survival. Growth will resume or even catch up at faster rates than normal when the nutritional deficits are remedied. This sensitivity to health and environmental constraints makes growth an excellent indicator of the adequacy of nutrition and the health of individuals and of populations. As basic indicators of health, pediatricians compare the attained stature and weight of children and their rates of growth with the expected values for healthy children or with growth standards.

In public-health studies comparing different populations or countries, the percentage of young children with very short stature (stunting) and the percentage of those whose weight is very low for how tall they are (wasting) are important indicators of nutritional and health conditions affecting children. In such studies, the average age at menarche, or of other maturational events, may be used to indicate the adequacy of general health and nutritional conditions.

Some examples of the average age at menarche from different countries are given in Table 1. Average ages of menarche greater than 13.5 years are usually considered to be associated with some general nutritional or health constraints in the country. In the case of Nepal, these issues are probably complicated by the people living at very high altitude, which may affect growth and maturation because of the reduced availability of oxygen to the body.

When nutritional energy (calories from food) is in excess of what the body uses and what is expended in physical activity, it is stored in adipose tissue. This fat tissue is accumulated within the body and subcutaneously (under the skin). The growth in weight of children and measurements of the thickness of the subcutaneous fat by calipers are used as indicators of overweight and obesity. Sometimes the weight of children is expressed as an index relative to stature (calculated by dividing the weight, in kilograms, by the square of stature, in meters) to yield the body mass index (BMI). BMI standards are also commonly used to define overweight and obesity and to relate these conditions to various health outcomes.

Physical growth includes many aspects of the biological development of children that can reflect genetics, nutrition, health, and the environment. The aspects of physical growth are central to the child's progress toward adulthood, and they inevitably interact with psychological, behavioral, and social aspects of the developing child.