COOP Logo

© 1997-2023 FNX Corporation and Trustees of Dartmouth College. All Rights Reserved.

CHAPTER 6: Growth

Adolescence is an exciting time. In a few years boys change into young men and girls into young women. During this time you start to examine how you feel about people, problems, life, and love. You become more aware of your sexuality. You will notice that you think about things a lot differently during adolescence. Girls start to notice the changes in their body beginning at about age 10; boys begin at about age 12. But the starting time is different depending on when your parents started (heredity), the foods you eat, and the amount you exercise. (Under-eating and over exercising may slow down your growth.) Nothing is wrong or abnormal if your body changes begin earlier or later. But by age 15 all boys and girls should have noticed some changes. This period in your life is called puberty.

At the time of puberty, a small gland in your brain called the pituitary (pit-ew-it-airy) sends messages to other parts of your body by hormones. Hormones are special chemicals made by your body which help your reproductive organs (sexual parts) mature.

Changes from Girl to Woman

You may notice a change in your breasts first. The nipples look as if they are swollen. One breast may seem larger than the other and this is very normal. You will have a spurt in height and weight. Your hips will get broader and hair will grow under your arms and in your pubic area. You may notice that your hair and skin feel more oily and you develop acne. You may sweat more. You will also have your first menstrual period, the monthly flow of blood that occurs in women. (See Menstruation)

Women have two ovaries located in the right and left lower abdomen (belly). An egg is released each month by one ovary and travels down to the uterus (womb). The release of this egg is called ovulation and occurs about 12 to 14 days before the monthly bleeding or period. Hormones cause the lining of the uterus to build up in preparation for nourishing a baby. If the woman does not get pregnant, the lining is not needed and it is shed. Blood flows from the uterus through the vagina and this is your period.

Changes from Boy to Man

Boys usually go through puberty later than girls. A boy's testes begins to make more male hormones. His penis grows all during the teenage years. Hair will grow at the base of the penis, in the armpits, and on other parts of the body including the face. The boy's voice deepens. Sometimes it sounds like it goes up and down as he talks.

The testes which are often called the "balls" hang in the scrotum or sac. The testes begin to produce sperm. If the male is stimulated, the penis gets stiff and erect and then sperm will flow from the testes through very small tubes and get forced out from the end of the penis. Urine and semen do not mix because the tube from the bladder shuts closed with erections. If you want to read more about sex, please look at the section on Sexual Questions.

How Tall Will You Be?

Both boys and girls go through a growth spurt about two years after puberty. The growth spurt may be 3-4 inches in a year. You can get an idea about how tall you will be by looking at the rest of your family members. If your family members are tall, you will probably be tall. If some of your relatives are tall and some small, it is harder to guess how tall you will be. However, doctors have charts that can tell you how you are growing compared to others of your age and sex. Remember, big differences in kids are normal. Healthy 15 year old boys can be normal and as short as 5 feet and as tall as six feet-two inches; for girls of the same age, we expect 95% of them to be between 4 feet 11 inches to 5 feet 11 inches.

Of 100 kids who are concerned that they are not growing, about 98 have nothing to worry about. The growth problem is just because of their family histories. A doctor can do other tests to check on growth if there seems to be another cause.

How You Feel and Think

A child cares a lot about what his family thinks. A young adolescent will begin to be very interested in what other friends think. Older adolescents will care about how their actions affect others and how they will fit into society. These changes may sound simple but they are often really hard because you:

  • differ so much from everyone else (remember the height differences as an example).
  • no one has ever "test-driven" your mind, your body, and your views of life (you are the test-driver and owner and you don't know what is on the road ahead).
  • It is normal to experiment, sometimes.
  • It is normal to worry about what is ahead, sometimes.
  • It is normal to feel scared, sometimes.
  • It is normal to make mistakes, sometimes.
  • It is normal not to fit in a lot of the time.

The good news is that everyone wants you to succeed. You are important. You are the next generation. So don't be afraid to ask a lot of questions of your parents and other adults. (READ PROBLEM SOLVING.)

We have tried to make the How's Your Health error-free. However, those involved in its preparation can not warrant that all of the information is accurate and complete. When you use How's Your Health as a guide for your health and medical care, be sure to discuss any questions about it with your doctor, nurse, or other health care worker.


To choose another chapter, click the 'BACK' button.


Last reviewed: January 2023 © 1997-2023 FNX Corporation and Trustees of Dartmouth College. All Rights Reserved.