1. Normal Pubertal Development

The application of growth charts to adolescents requires an understanding of normal growth and development during puberty. More than 40 years ago, James Tanner and associates began describing the normal physical changes that occur during puberty. Tanner has noted that "the only thing that is constant about puberty is change."

Besides the obvious differences of the genitalia and secondary sex characteristics between males and females, there are also differences between individuals who develop early compared to those who develop later in their teenage years. This context of change must be appreciated when using growth charts with adolescents.

Tanner and colleagues serially measured and photographed a large number of normal British males and females to determine the physical changes that adolescents experience as they grow from boys to men and from girls to women.

Five recognizable stages of pubertal changes (called Tanner Stages, or Sexual Maturity Ratings -- SMR) have been described for males and for females.

For boys, the three physical elements of sexual maturity rating are:

the size of the testes
the length of the penis
the development of pubic hair

The two physical elements of sexual maturity rating for girls are:

breast development
pubic hair development