What is delayed puberty?
Delayed puberty is when pubertal signs do not begin within the expected age range — by the common definition, no pubertal sign appearing by age 13 in girls and 14 in boys. These children still have a childlike appearance while their peers develop and enter the growth spurt, and they are usually shorter than peers.
Delayed puberty is often not an illness but maturation running at the late end of normal. Even so, evaluation is recommended to rule out the few underlying causes.
The most common cause: constitutional delay
The most common cause of delayed puberty is a benign variation called “constitutional delay of growth and puberty”. In these children bone age is behind calendar age; that is, the biological clock runs more slowly. There is usually a similar family history (the mother may have had a late first period, the father may have grown late). These children enter puberty and the growth spurt late, but keep growing after peers have stopped, mostly reaching a normal — and familial-target-appropriate — adult height.
This pattern is especially common in boys and is known as the “late bloomer”. A delayed bone age here is not bad but actually a reassuring finding: there is still growth in the hand.
Other causes and assessment
Among the less common causes of delayed puberty are chronic illnesses, inadequate energy intake or excessive exercise (especially in some athletes), poor nutrition and hormonal problems. To distinguish these causes, paediatric endocrinology uses the growth history, bone age, necessary hormone tests and a clinical examination together.
The aim of the assessment is to spare the common, benign constitutional delay from unnecessary intervention while not missing the causes that need addressing. In most cases follow-up and reassurance are enough; if deemed necessary, the doctor considers the options.
Approaching the “late bloomer”
For a child experiencing constitutional delay — that is, a “late bloomer” — the most challenging period is often the start of middle and high school: while peers develop rapidly and enter the growth spurt, the child still looks shorter and more childlike. This can affect confidence, especially in sport and in social settings. Yet these children, with their delayed bone age, usually have a longer period of growth ahead, and most keep growing after peers have stopped, reaching their familial target height.
For families, the most helpful approach is to explain calmly to the child that this is not an illness but a difference in timing. Setting expectations by maturation rather than calendar age; continuing sport in a maturity-sensitive way (see bio-banding); and keeping regular follow-up with a doctor when needed are all supportive. In most cases time is the best treatment; but if there is clear distress or doubt, a paediatric endocrinology assessment should not be delayed.