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Am Fam Physician. 1999;60(1):223-224

See related article on disorders of puberty.

What is puberty?

Puberty is the time in life when a young person starts to become sexually mature.

In girls, puberty may start as early as 8 years of age, but it usually starts around 11 years of age. In boys, it begins around 12 years as age, but may start as early as 9 years of age. This is a process that goes on for several years. Most girls are physically mature by about 14 years of age. Boys mature a year or two later.

What are the first signs of puberty in boys and girls?

The first sign of puberty in most girls is breast development. The first sign of puberty in most boys is an increase in the size of the testicles.

Does sexual development have a typical pattern?

Yes. In girls, breasts develop first. Then, hair starts growing in the pubic area. Next, hair starts growing in the armpits. In girls, acne usually starts around 13 years of age. Menstruation (the period) usually happens last.

In boys, the testicles and the penis get bigger first. Then hair grows in the pubic area and the armpits. A small amount of breast tissue might develop at this time. The voice becomes deeper. Muscles grow. Last, acne and facial hair show up.

Does sexual development always follow the same pattern?

No. Some children can have different patterns. Some girls develop breasts at a very young age but have no other signs of sexual development. A few children have pubic and armpit hair long before other signs of sexual growth. These changes in pattern usually don't mean the child has a problem, but it's a good idea to visit your doctor to find out for sure.

What is early puberty? What causes it?

You may want to visit your doctor if a young girl:

  • Develops breasts and pubic hair before 8 years of age.

You may want to visit your doctor if a young boy:

  • Has an increase in testicle size and penis length before 9 years of age.

Early puberty is sometimes called precocious or premature puberty. In most cases, early puberty is just a variation of normal puberty. In a few cases, there may be a medical reason for early puberty.

What is delayed puberty? What causes it?

Puberty may be late in girls who have the following signs:

  • No development of breast tissue by age 14

  • No periods for 5 years or more after the first appearance of breast tissue

Puberty may be late in boys who have the following signs:

  • No testicle development by age 14

  • Development of the male organs isn't complete by 5 years after they first start to develop.

Sometimes a medical reason causes delayed puberty, but sometimes not. For example, malnutrition (not eating enough of the right kinds of food) can cause delayed puberty.

Do early and late puberty run in families?

Both early and late puberty can run in families. There can be other causes, too.

How will my doctor know what is causing the change in puberty pattern?

Your doctor will talk to you and your child. Then your child will have a physical exam. The doctor might suspect a cause for the puberty variation and order some tests. Sometimes the cause can't be found even after several tests.

These are some tests your doctor might order for your child:

  • Blood tests to check hormone levels

  • An x-ray of the wrist to see if bone growth is normal

  • A CT or MRI scan (special pictures) of the head to look for a tumor or brain injury

  • Chromosome (gene) studies

Are early and late puberty treated?

In most children, no cause is found. It's just a variation of normal puberty. No treatment is needed. In some children, a medical cause is found and treated. For example, if the reason for late puberty is lack of hormones, hormone shots can help.

What can I do to help my child?

The way children see their own body has a lot to do with their self-esteem. It's important to let children know they're OK the way they are and that you love them that way. You can let your child know that he or she is normal (when the tests are normal). You can tell your child that you'll help him or her with any problems (if the tests show a problem). If you need help or if you think your child may need counseling, talk to your family doctor.

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Copyright © 1999 by the American Academy of Family Physicians.

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