Tanner scale

The Tanner scale (also known as the Tanner stages or sexual maturity rating (SMR)) is a scale of physical development as children transition into adolescence and then adulthood. The scale defines physical measurements of development based on external primary and secondary sex characteristics, such as the size of the breasts, genitals, testicular volume, and growth of pubic hair. This scale was first quantified in 1969 by James Tanner, a British pediatrician, after a two-decade-long study following the physical changes in girls undergoing puberty.

Due to natural variation, individuals pass through the Tanner stages at different rates, depending in particular on the timing of puberty. Among researchers who study puberty, the Tanner scale is commonly considered the "gold standard" for assessing pubertal status when it is conducted by a trained medical examiner. In HIV treatment, the Tanner scale is used to determine which regimen to follow for pediatric or adolescent patients on antiretroviral therapy (adult, adolescent, or pediatric guidelines). The Tanner scale has also been used in forensics to determine aging, but its usage has decreased due to lack of reliability.