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Physical Development: What’s Normal? What’s Not?

​Two boys or girls exactly the same age can start or end puberty years apart, yet still fall within what is considered "normal" growth. The timing and speed of a child's physical development can vary a lot, because it is determined largely by the genes inherited from the parents.

Teen Growth Pattern

Whatever pattern a teen's growth follows, it is during the pubertal years that your son or daughter grows tall more rapidly than at any other time in a child's life.

  • Girls: On average, rapid growth occurs around age eleven and a half, but it can begin as early as eight or as late as fourteen.
  • Boys: Usually trail behind by about two years—this is why thirteen-year-old girls can, for a time, be a head taller than thirteen year old boys.

Here's What Usually Happens

The hands and feet grow first, frequently causing an awkward body appearance. Until the arms and legs catch up, teenagers may seem to trip over their own feet. Next, the boys' shoulders and girls' hips get wider and the trunk of the body lengthens. The bones in the face grow too—particularly the lower jaw—bringing about very noticeable changes.

To help you recognize the many changes that can take place during puberty, first remember that every year since the age of two or three, your child has grown an average of about two inches and gained about five pounds. However, while in puberty you can expect that rate to double.

Growth in both boys and girls slows considerably soon after puberty is complete. Having gained nearly all of their adult height during puberty, once the period of development is over, most teens grow no more than another inch or two. You may need to check with your pediatrician to see if your child has completed his or her pubertal development.

When to Speak to the Pediatrician:

For a boy or girl to be slightly less developed or more developed than other kids the same age is rarely cause for alarm. But if a child seems significantly different from others his or her age, parents should speak with their pediatrician, so that their child can be checked for—and most likely rule out—any medical problems. Chances are, it's the pediatrician who will bring these differences to the parents' attention.

Blame It on Hormones

Hormones, chemical messengers produced by the body's glands, travel through the bloodstream to affect:

  • Growth
  • Sexual characteristics
  • The ability to have children
  • Metabolism
  • Personality
  • Mood swings

Although the trigger that starts puberty is not yet fully understood, sometime between the ages of seven and eleven in girls, and nine and a half to thirteen and a half in boys, the pituitary gland at the base of the brain releases two hormones that signal a girl's ovaries to start producing the female sex hormone, estrogen, and a boy's testicles to start producing the male sex hormone, testosterone.

About Sex Hormones:

Sex hormones instruct reproductive organs to develop or mature in preparation for one day being able to have children. Estrogen and testosterone also cause the development of secondary sex characteristics, which lead to male-female differences, such as women's breasts and rounded hips, and men's facial hair and muscle development. The maturing ovaries and testicles make increasing amounts of sex hormones, further promoting the process of puberty.

Additional Information:

Last Updated
Section on Endocrinology (Copyright © 2014 American Academy of Pediatrics)
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