About puberty

Puberty is when a child’s body begins to develop and change as they become an adult.

It usually starts from the age of 8 years in girls and from the age of 9 years in boys. The average age for girls to start puberty is 11, while for boys the average age is 12.

Puberty happens because of changes in the body’s hormones (chemicals that coordinate bodily functions). Puberty is a natural process and it can be delayed for different reasons.

First signs that your child is entering puberty

In girls, you might see breast enlargement and pubic or underarm hair. Periods usually start after these changes have taken place.

In boys, you might see a larger penis and testicles (also called testes or balls), a deeper voice and a more muscular appearance.

In both boys and girls, there will be a time of rapid growth (growth spurts). 

Teenagers may also experience changes in emotions and mood swings as they go through puberty.

About delayed puberty

Delayed (or late) puberty is defined this way:

  • Girls: no signs of puberty by the age of 13 years.
  • Boys: no signs of puberty by the age of 14 years.

It affects approximately 2% of adolescents and is more common in boys.

Causes

Late puberty can happen for the following reasons.

  • Sometimes it is genetic (it runs in the family).
  • Sometimes it is caused by a long term illness.
  • Occasionally it is caused by a delay in hormones because the child’s body has a problem making or recognising puberty hormones.

When to seek medical help

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Contact your GP if you notice any of the following.

  • Your son is 14 years old and is not displaying any of the signs of puberty described in this leaflet.
  • Your daughter is 13 years old and is not displaying any of the signs of puberty described in this leaflet.
  • Your son or daughter has started puberty, but it does not progress or it stops abruptly.
  • Your child’s signs of puberty appear in an unusual order. For example your daughter starts her periods before her breasts start to develop.

Assessing delayed puberty

Your GP may refer you to a specialist if they think there might be an underlying cause of delayed puberty that needs investigation.

The specialist is likely to be a general paediatrician (child health specialist) or a paediatrician with a special knowledge of hormone problems (known as an endocrinologist).

What happens at the paediatric clinic

At the paediatric clinic your child will be given a physical examination. This physical examination is an important part of the assessment.

  • A doctor will measure your child’s height and weight.
  • They will carry out a thorough examination to ensure your child has no signs of underlying health problems.
  • They will also examine your child for signs of puberty.  This includes checking for breast tissue in girls and measuring size of the testes (‘balls’) in boys.

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Get in touch with the paediatrics administration team before your child’s appointment if your child feels they would be more comfortable having this examination with a doctor of the same sex (see Contacts section). You can also ask for a chaperone (a neutral observer) to be present at the appointment if you wish.

Your child will also be given some tests.  These might include the following.

  • A blood test to check hormone levels and check for signs of other medical problems.
  • An X ray of their hand to check their ‘bone age’. This helps determine their potential to grow and predict their likely adult height.
  • An ultrasound or a different imaging test is occasionally used to check for problems with glands or internal organs.

Treatment

We usually recommend treatment with medication if the lack of development is causing problems, such as significant distress to your child. 

Medication will only be prescribed by a specialist children’s hospital after a period of observation and follow up.

Contact information

Paediatric Admin Team, Monday to Friday 9am to 5pm

Telephone:

020 8934 6403