Early or delayed puberty

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

Signs of puberty include:

• girls developing breasts and starting periods
• boys developing a larger penis and testicles, a deeper voice and a more muscular appearance

The average age for girls to start puberty is 11. But it's normal to begin at any point between the ages of 8 and 13.

The average age for boys to start puberty is 12. But it's normal to begin at any point between the ages of 9 and 14.

There's usually no need to worry if puberty does not start around the average age. But it's a good idea to speak to your GP for advice if it starts before 8 or has not started by around 14.

In some cases, early puberty or delayed puberty could be a sign of an underlying condition that may need treatment.

Early puberty

Early puberty, also called precocious puberty, is when:

• girls have signs of puberty before 8 years of age
• boys have signs of puberty before 9 years of age

Some children may develop signs of puberty at a young age, but not others.

For example, girls may start periods before the age of 8 but have no breast development.

Talk to your GP if this happens to your child.

Causes of early puberty

It's not always clear what causes early puberty. It may be something that runs in your family.

Sometimes the cause can be:

• a problem in the brain, such as a tumour
• damage to the brain as a result of an infection, surgery or radiotherapy
• a problem with the ovaries or thyroid gland
• a genetic disorder, such as McCune-Albright syndrome

Early puberty mostly affects girls and often has no obvious cause. It's less common in boys.

Tests and treatments for early puberty

Your GP may refer you to a specialist if they think there might be an underlying cause.

You may need tests, such as:

• a blood test to check hormone levels
• a hand x-ray to help determine likely adult height
• an ultrasound scan or MRI scan to check for problems such as tumours

Treatment for early puberty includes:

• treating any underlying cause
• using medication to reduce hormone levels and pause sexual development

Treatment with medication is usually only recommended if early puberty could cause emotional or physical problems. For example, very short stature or early periods in girls. These may cause a lot of distress.

Delayed puberty

Delayed puberty is when:

• boys have no signs of testicular development by 14 years of age
• girls have not started to develop breasts by 13 years of age
• girls have developed breasts but their periods have not started by 15

Causes of delayed puberty

It's not always clear what causes delayed puberty. It may be something that runs in your family. Delayed puberty is more common in boys.

Sometimes the cause can be:

• a long-term illness, such as cystic fibrosis, diabetes or kidney disease
• malnutrition, from an eating disorder or a condition such as cystic fibrosis or coeliac disease
• a problem with the ovaries, testes, thyroid gland or pituitary gland
• a disorder of sexual development, such as androgen insensitivity syndrome
• a genetic condition, such as Kallman syndrome and Klinefelter syndrome

Tests and treatments for delayed puberty

Your GP may refer you to a specialist if they think there is an underlying cause.

You may need tests, such as:

• a blood test to check hormone levels
• a hand x-ray to help determine likely adult height
• an ultrasound scan or MRI scan to check for problems with glands or organs

Treatment for delayed puberty includes:

• treating any underlying cause
• using medicine for a few months to increase hormone levels and trigger the start of puberty

Treatment with medicine is recommended if the lack of development causes problems, such as serious distress.