Puberty and Hormones

What causes delaued or precocious puberty?
on Thu 26 Jul


You might be surprised to know that we now regard the average age of puberty as being at the age of around 11 for girls and 12 for boys. This has dropped steadily by about 4 to 5 months with every passing decade.  A German study found that the average age of puberty in girls was


  • 16.6 years in 1860
  • 14.6 in 1920
  • 13.1 in 1950
  • 12.5 in 1980
  • and 10.5 by 2010


it is not known why this should be the case, theories have been expounded around better health;  a higher BMI;  a diet with increased sugar and fat; declining physical activity or chemicals in the environment that act on hormones but there no set conclusions.


How do our hormones affect puberty?

What we do know is that the hypothalamus – a grape-sized structure in your brain - triggers puberty by producing gonadotrophin releasing hormone (GnRH) which stimulates the pituitary gland to release two hormones


  • Follicle Stimulating Hormone (FSH)
  • Luteinising Hormone (LH)


These are carried in the blood to the testicles and the ovaries which are then switched on to the development procedure which starts sexual maturity.


Precocious Puberty

Five times more common in girls than boys, precocious puberty in the UK occurs in 1 child per 5,000 to 10,000.


If puberty begins before the age of 8 in girls and 9 in boys it is known as “precocious puberty” – tell-tale signs of precocious puberty include:


In boys and girls

  • Body odour which is more “adult”
  • Pubic or underarm hair
  • A rapid growth spurt
  • Acne


In girls

  • The beginning of menstruation
  • Breast development


In boys

  • The enlargement of the testicles and penis
  • Facial hair
  • Voice deepening


Delayed Puberty

Occurring in 3% of children, this is also referred to as CDGP and is diagnosed when there is no breast development in girls by the age of 13, or there is a lack of testes growth in boys by the age of 14.


90% of cases occur in children who are perfectly healthy but simply have a slower rate of development. Typically these children are shorter and thinner than their peers and have a family history of delayed puberty.


Diagnosis and treatment

Precocious puberty:

In 90% of girls and 50% of boys no underlying cause can be identified which means it is referred to as “idiopathic precocious puberty”.  However, a CT scan or MRI will be rule out specific rare causes such as a tumour in the brain, ovary or testicle.


Even if the cause is not attributable, the main aim of treatment will be to enable the child to achieve a normal height as precocious puberty can stunt the growth.  This is supervised by a paediatric endocrinologist to lower the sex hormone levels with the current approved treatment using drugs called LHRH analogues. These are injected monthly and block the production of sex hormones - usually having a positive effect within a year.


Delayed puberty:

If this is not occurring in children who generally have a slow rate of development doctors will check that this is not:


  • secondary to a chronic illness such as diabetes, cystic fibrosis or coeliac disease
  • caused by anorexia or severe stress
  • as a result of chromosomal disorders such as Turner Syndrome in girls or Klinefelter’s Syndrome in boys
  • caused by a tumour, trauma, surgery or radiation therapy to the head


A plain x-ray of the wrist can show a difference between the chronological age and the bone age and that there is a potential for growth. If necessary, puberty can be induced by short courses of low doses of oestrogen for girls and testosterone for boys.


I hope this is helpful.



Although every effort is made to ensure that all health advice on this website is accurate and up to date it is for information purposes and should not replace a visit to your doctor or health care professional.


As the advice is general in nature rather than specific to individuals Dr Vanderpump cannot accept any liability for actions arising from its use nor can he be held responsible for the content of any pages referenced by an external link


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