Physical Development in Adolescents

Physical Development: The Body’s Wonder Years

Most teens will probably tell you that “normal adolescent development” is an oxymoron. But despite the awkwardness that goes with the change from child to adult, the transition is usually a predictable one.

Physical development in adolescent girls

Age noticeable change usually begins and stops:

Increase in rate of growth – begins at 10 to 11 and stops at 15 to 16. If noticeable growth fails to begin by 15, see your doctor.

Breast development – begins at 10 to 11 and stops at 13 to 14. Noticeable development of breasts (one of which may begin to grow before the other) is usually the first sign of puberty. If change doesn’t begin by 16, see your doctor.

Emergence of body hair begins – Pubic: 10 to 11, underarm – 12 to 13. Stops at 13 – 14 (pubic) and 15 – 16 (underarm). Development of body hair is extremely variable and largely dependant on heredity. Pubic hair usually darkens and thickens as puberty progresses.

Development of sweat glands under arms and in groin: Begins at 12 or 13. Stops at 15 or 16. Sweat glands are responsible for increased sweating, which causes underarm odor, a type of body odor not present in younger children.

Menstruation: The change begins at 11 to 14 and stops at 15 to 17. Menstruation often begins with extremely irregular periods but by age 17, a regular cycle (3 to 7 days every 28 days) usually becomes evident. If menstruation begins before 10 or has not begun by 17, talk to your physician.

Adolescent Girl. Photo by Elena

Physical development in adolescent boys

Age noticeable change usually begins and stops:

Increase in rate of growth – begins at 12 to 13 and stops at 17 to 18. If noticeable growth fails to begin by 15, see your doctor.

Enlargement of genitals: Testicles and scrotum – change begins at 11 to 12 and stops at 16 to 17. Penis – 12 to 13 and 15 to 16. As testicles grow, the skin of the scrotum darkens. The penis usually lengthens before it broadens. Ability to ejaculate seminal fluid usually begins about a year after the penis starts to lengthen.

Emergence of body hair begins – Pubic: 11 to 12, underarm – 12 to 13. Stops at 15 – 16 (pubic) and 16 – 18 (underarm). Development of body hair is extremely variable and largely dependent on heredity. Development of hair on the abdomen and chest usually continues into adulthood.

Development of sweat glands under arms and in groin: Begins at 13 or 15. Stops at 17 or 18. Sweat glands are responsible for increased sweating, which causes underarm odor, a type of body odor not present in younger children.

Voice change: begins at 13 to 14. Stops at 16 to 17. Enlargement of the larynx, of voice box, may make the Adam’s apple more prominent. The voice deepens at 14 to 15, and may change rapidly or gradually. If childlike voice persists after 16, see your doctor.

(Source: American Medical Association Family Medical Guide, Random House).