Last updated on September 24, 2020
When I look up the Tanner Stages in other sources, they often say that stage 4 is when peak growth occurs; It’s also said by Tanner himself. Yours seems to be the only one that says growth slows to just 1-3 inches in stage 4. Why’s that?
Dr. Tanner’s first published a scale in 1962. The scale is based on genital development and pubic hair distribution. From that base, other characteristics were added to define the scale.
Based on the genitals only, the scale states:
Stage 1: Pre-adolescent. Testes, scrotum, and penis are of about the same size and proportion as in early childhood.
Stage 2: The scrotum and testes have enlarged and there is a change in the texture of the scrotal skin. There is also some reddening of the scrotal skin.
Stage 3: Growth of the penis has occurred, at first mainly in length but with some increase in breadth. There has been further growth of testes and scrotum.
Stage 4: Penis further enlarged in length and breadth with development of glans. Testes and scrotum further enlarged. There is also further darkening of the scrotal skin.
Stage 5: Genitalia adult in size and shape. No further enlargement takes place after Stage 5 is reached.[W. A. Marshall and J. M. Tanner, Variations in the Pattern of Pubertal Changes in Boys]
Based on pubic hair only, the scale states:
Stage 1: Pre-adolescent. The velus over the pubes is no further developed than that over the abdominal wall, i.e. no pubic hair.
Stage 2: Sparse growth of long, slightly pigmented, downy hair, straight or only slightly curled, appearing chiefly at the base of the penis.
Stage 3: Considerably darker, coarser, and more curled. The hair spreads sparsely over the junction of the pubes.
Stage 4: Hair is now adult in type, but the area covered by it is still considerably smaller than in most adults. There is no spread to the medial surface of the thighs.
Stage 5: Adult in quantity and type, distributed as an inverse triangle pattern. Spread to the medial surface of the thighs but not up the linea alba or elsewhere above the base of the inverse triangle.[W. A. Marshall and J. M. Tanner, Variations in the Pattern of Pubertal Changes in Boys]
Notice that growth rates are not assigned to the stages; rather, the doctors first created the stages and then applied them to boys to see how their growth patterns lined up with the stages. The study readily admits that the sample they used was not broad — participants were volunteers from the poor quarters of London.
When focused on growth, there are two definitions used for stage 4. Dr. Tanner used the peak growth point as the transition point from stage 3 to stage 4. In other words, stage 3 is the time the growth rate increases, and stage 4 is the time the growth rate decreases. The problem with this definition is that some boys can have more that one growth spurt. You’ll see some site misquote the definitions to say that peak growth can come during stage 4; that is incorrect, it marks the start of stage 4. This definition makes stage 3 last about six months and stage 4 lasts about three years. Another annoyance is that this definition is different from what is used for girls.
The second definition uses the childhood rate of growth as the baseline. Thus, stage 3 is when the growth rate is above the childhood rate and stage 4 is when the growth rate drops back down to childhood rate and below. It isn’t as popular, but I like this one better because it handles unsteady growth spurts and it happens to make the stages more equal in length. I personally think it lines up better with the genital and pubic hair markers as well. Another reason I prefer this definition is that it is the same definition used for girls.
In the end, it doesn’t matter which definition is used, so long as you understand which definition is being used.