Tanner stage

The Tanner stages (also known as the Tanner scale) are stages of physical development in children, adolescents and adults. The stages define physical measurements of development based on external primary and secondary sex characteristics, such as the size of the breasts, genitalia, and development of pubic hair.

Due to natural variation, individuals pass through the Tanner stages at different rates, depending in particular on the timing of puberty.

In HIV treatment, Tanner staging is used to determine which treatment regimen to follow (adult, adolescent, or pediatric).

The Tanner stages were first identified by (and named for) James Mourilyan Tanner.

It is commonly misbelieved that the Tanner stages measure the entire course of puberty. However, this is not true, bearing in mind that the internal reproductive organs begin changing much earlier, and finish changing much later, than the changes visible from the outside. Scientifically speaking, puberty begins at an average age of 9 in females and 10 in males, and ends at an average age of about 22. This is based on 'puberty' being defined as the period just encompassing all changes in the reproductive organs associated with the final activation of the hypothalamic-pituitary-gonadal axis, beginning when gonad growth begins to accelerate, and ending when all gonad growth is complete.