Physical Growth

Physical growth usually refers to changes in size or mass; so it is correct to say that a child grows in stature (height) or body weight. Even though most people usually think of growth at the level of the whole child, the cells and internal structures that make up the child also grow, primarily by increasing in number or size. Consequently, auxologists (those who study child growth) may be interested in the growth of bones to help understand fractures and osteoporosis; the growth of the heart walls to help understand hypertension (high blood pressure) and heart disease; or the growth of adipose tissue (body fat) to help understand obesity.

The measurement of body dimensions such as those used in growth studies is called anthropometry. Past growth is usually measured as the size attained at a chronological age, for example the weight of a child at eight years old. Assessment of the rate of growth requires that a body dimension, such as weight, be measured twice over a period, and then the change is expressed in terms of the increment or velocity of growth, for example in pounds or kilograms per year.

Some physical changes in childhood are more complicated than just size or mass. These changes include alterations in body structures and functions and can be termed development. Physical developmental changes are as diverse as the closing of the fontanels (soft spots) in a baby's skull, the erupting of teeth, learning to walk, or the deepening of the voice of boys during adolescence.

Some developmental changes are considered maturational, or indicators of physical maturity. Maturation is the progression of developmental changes toward the characteristics of adults. Physical maturation occurs from the time of conception, but some of the most commonly recognized indicators of maturation become apparent during adolescence. Changes in body shape, breast development in girls, pubic hair development in both genders, and development of facial hair in boys are visible indicators of maturation toward adult appearance of the body, and they signal adult reproductive functioning. The cessation of the growth of long bones, associated with the final attainment of adult stature is also a maturational event.

Although growth and maturation are certainly related, distinguishing between them is important because some physiological and hormonal processes affect growth and maturation differentially, as do some diseases. It is easy to observe that children of the same size can differ in maturational status and that fully mature individuals (adults) can be of different sizes.