Child Growth and Development - Puberty and the Teen Years

Parents whose children are approaching puberty will likely remember their own young adult years, and not always fondly. This is a time of intense change: physically, emotionally, and mentally. Parents can use their own experience to help guide their children through these often difficult years.

The American Academy of Family Physicians (AAFP) also provides insights into the timeline for the intense growth and development during this stage.

Understanding is certainly key to helping children with this complicated transition. These changes can be overwhelming, confusing, and frustrating, but offering age-appropriate information, honest answers, and clear communication can help assure children that their growth and development is a normal part of the process of growing up.

The Tanner stages of puberty are used to mark milestones in physical development during puberty.

In stage 1, the pre-puberty stage, neither boys nor girls have marked pubic hair and girls have only slightly elevated breast tissue. Boys’ testes do not undergo growth, and there is not much development at this stage.

Stage two (from around 11 to 12 years; girls enter and exit all stages sooner), is marked by girl’s breast bud development and growth of hair along the labia. Girls may grow 3 inches in height. Boys experience a reddening and thinning of the scrotum, testes and pubic hair will grow, and body fat will decrease.

During stage 3 (about age 12 ½ to 13), girls’ breasts continue to grow and they hit their peak height growth. Boys experience growth of the penis and testes and develop more and thicker hair and will gain 3 inches in height as well as muscle mass.

Stage 4 for girls, between the ages of 13.1 and 13.4 years, is marked by a projection of breast tissue, adult-type pubic hair, and deceleration in growth. Boys continue growth of the penis and glands and also develop adult-type pubic hair, and are at their peak of growth.

Stage 5 lasts from about 14 ½ to 16 years in girls, who develop adult-type hair and adult breast contour. Boys’ stage 5 lasts from almost 15 to 17 years; they develop adult genitalia, facial hair, and growth decelerates and stops. Muscle mass, though, keeps increasing.

Girls will experience their first menstruation during puberty, too; the age varies, however.

As if these rapid and sometimes confusing physical changes are not enough for teens, there comes emotional instability, outbursts, and lack of judgment. Even a fully-developed adult brain has some trouble adjusting to rapid changes like these, but for teens, whose brains are still developing, things are that much more difficult.

Dr. Andrew Garner of the American Academy of Pediatrics notes that “the important concept here is that the adolescent brain is still developing and not yet fully mature,” and that some parts of the brain do not reach full development until age 24.

What seems like teenage erratic behavior may really be caused by the disconnect that happens when parts of the brain develop out of sync. That doesn’t excuse teen behavior, but it may help explain it. Knowing that teens may be in situations where the less mature parts of the brain could take over means that parents have to work with their teens to avoid these situations in the first place.

What is Puberty?

Puberty and the teen years go hand in hand, but puberty is often defined as a clinical process. The AAFP defines puberty as “a process leading to physical and sexual maturation that involves the development of secondary sexual characteristics as well as growth, changes in body composition and psychosocial maturation.”

The teen years, 13 to 19, are also marked by physical changes, but there are emotional and social aspects to teens’ growth and development. The teen years can be especially difficult for parents and teenagers.

Previously close relationships may become strained, new roles develop, and communication can break down as teens feel misunderstood and confused.