Girls reach their full height when they are about 18 years old, but boys keep growing taller for a few more years.
There are two periods in your life when you grow very rapidly. The first period began right after you were born and lasted until you were about six months old. The second period occurs when you reach your early teens. Girls grow faster than boys until they become teen-agers, then boys catch up and grow faster and stronger.
Your head stops growing earlier than the rest of you. When you were a newborn baby, you looked as if you were almost all head. By the time you were 10, your head was nearly full size.
The bones of your arms and legs were short when you were a baby. When you reached the age of 9, your bones started to grow rapidly and will keep growing until you reach your full height.
Besides growing taller, your body changes in other ways. When a boy is about 13 years old, his voice begins to get deeper and he may begin to grow a beard. About the age of 13, a girl’s body begins to look and function like a woman’s. Inside the bodies of both teen-age girls and boys, important changes are taking place, changes that make it possible for boys and girls, when they are older, to become fathers and mothers.