Early and delayed puberty

Puberty begins in girls between 8 and 13 and in boys between 9 and 14. If signs appear earlier or, conversely, do not arrive on time, it is worth having the child seen. Most often a normal variant is found, but the assessment matters: in some cases there is an underlying condition that needs treatment, and the earlier it is addressed, the better for the child's final height and wellbeing.

Early puberty

This means signs appearing before age 8 in girls and before age 9 in boys.

• in girls: breast development, pubic hair, periods;
• in boys: enlargement of the testes and penis, pubic hair, voice change;
• in both: accelerated growth, body odour, acne, mood changes.

The least visible risk is not the signs themselves but final height: the child shoots up and looks taller than their peers at first, but the growth plates close earlier, and as an adult they end up shorter than they would have been. The second half of the problem is psychological: the body changes at an age when the child is not ready for it.

Causes

• in most girls no cause is found — it is simply an early start;
• in boys, an early start far more often has a specific cause, so investigation is mandatory;
• central nervous system disorders — tumours, the effects of injury, radiotherapy, hydrocephalus;
• adrenal and gonadal disorders, congenital adrenal hyperplasia;
• hypothyroidism;
• contact with hormonal preparations — adult creams and gels;
• excess weight, which brings the start forward in girls;
• certain genetic syndromes.

Variants that are not true early puberty

• isolated breast development in a girl under 2 — usually resolves by itself;
• isolated appearance of pubic hair without other signs;
• both need monitoring, but usually not treatment.

Delayed puberty

This means no signs by 13 in girls and by 14 in boys, or puberty starting and then stalling, or a girl having no periods by 15–16.

Causes

• constitutional delay — the most common variant, especially in boys; there is often the same history in a parent. Puberty comes later but fully, and final height is not affected;
• chronic conditions — coeliac disease, inflammatory bowel disease, kidney, heart or lung disease, poorly controlled diabetes;
• inadequate nutrition, eating disorders, very intensive sports training;
• hypothyroidism;
• pituitary disorders;
• primary gonadal failure — Turner syndrome in girls, Klinefelter syndrome in boys;
• the effects of cancer treatment;
• Kallmann syndrome — delayed puberty combined with an impaired sense of smell; worth noting specifically.

When to see a doctor

• signs of puberty appear in a girl before 8 or a boy before 9;
• there are no signs in a girl by 13 or a boy by 14;
• periods have not started by 15–16;
• puberty started and then stopped;
• the child's growth rate has changed sharply, up or down;
• headaches, visual changes or seizures have developed — reason to attend promptly;
• the child is distressed by being different from their peers;
• there is weight loss, diarrhoea or persistent tiredness — a chronic condition is possible;
• a boy's delayed puberty comes with a poor sense of smell.

How it is investigated

The basis is the growth trajectory: the doctor will plot a curve from all previous measurements, so bringing records from the child health book is very helpful. Then:

• assessment of pubertal stage on the standard scale;
• a hand X-ray to determine bone age — a simple and highly informative test;
• hormones: LH, FSH, oestradiol or testosterone, thyroid function, prolactin;
• stimulation tests if the mechanism needs clarifying;
• pelvic ultrasound in girls, testicular ultrasound in boys;
• brain MRI in early puberty, particularly in boys, and where pituitary disease is suspected;
• karyotype if a genetic syndrome is suspected;
• coeliac screening, full blood count and inflammatory markers in delayed puberty.

Treatment

• in early puberty — medication that temporarily halts the process (GnRH analogues). These are used where there is a risk of reduced final height or where the child is struggling psychologically. After stopping, puberty resumes and fertility is unaffected;
• treating the cause — tumours, adrenal disorders, hypothyroidism;
• in constitutional delay — most often simply monitoring, because it will happen on its own. Occasionally, where distress is significant, a short course of sex hormones is used to start the process;
• in primary gonadal failure — ongoing hormone replacement;
• treating the chronic condition and correcting nutrition — often this is enough;
• psychological support for both child and parents.

Common questions

Will it affect height? In early puberty, yes — final height can be lower, which is why treatment is sometimes used. In constitutional delay, height is usually unaffected.

Will it affect having children? In most variants, no. Treatment with GnRH analogues is reversible.

Is diet or screen time to blame? Excess weight does bring puberty forward in girls. The other common explanations have no evidence behind them.

Should we just wait? Watchful waiting is also a decision, but it should be made by a doctor after assessment, not by parents alone.

Online consultation

In an online consultation the doctor plots your child's growth from your records, reviews which signs appeared and in what order, explains what the hand X-ray is for, and draws up the list of investigations — distinguishing situations that need prompt attention from those that allow calm monitoring.

This material is for information only and does not replace a medical consultation.