Puberty is the only major developmental process that families are expected to interpret without a manual, at exactly the age when the child concerned would rather not discuss it. So here is the manual.
Puberty happens in an order
This matters more than the ages. The body follows a sequence, and it is a departure from the sequence that is often more meaningful than a departure from the average age.
In girls
- Breast budding (thelarche). A firm, sometimes tender disc under the nipple, often on one side first. This is the true start.
- Pubic hair, usually a few months later.
- The growth spurt, early in the process, which is why girls often overtake boys at eleven and are overtaken again at fourteen.
- First period (menarche), typically about two to two and a half years after breast budding.
In boys
- Testicular enlargement. The true start, and the one nobody sees. A volume of about 4 ml, roughly the size of a large grape.
- Pubic hair, then penile growth.
- The growth spurt, comparatively late, which is why a boy can look “behind” his classmates for two years and then gain 25 cm.
- Voice change, facial hair, acne. All late signs.
Note that in boys the first sign is internal. A boy who has facial hair and a deep voice has been in puberty for a long time; a boy whose testes have just begun to enlarge has started, even though nothing visible has happened.
The usual age windows
| Girls | Boys | |
|---|---|---|
| Puberty normally begins | 8 – 13 years | 9 – 14 years |
| Considered early if before | 8 years | 9 years |
| Considered delayed if nothing by | 13 years | 14 years |
| First period | 10 – 15 years | n/a |
Indian data suggest the average onset in girls has drifted somewhat earlier over the last two decades, as it has in most countries. Earlier is not automatically abnormal, but earlier than these thresholds deserves an assessment.
What actually concerns an endocrinologist
Not the calendar alone. These are the patterns that change the conversation:
- Rapid progression. Puberty that moves through its stages in months rather than years, regardless of when it started.
- Puberty with a growth spurt at a young age. A seven-year-old who is suddenly the tallest in the class is not doing well. An early spurt usually means an early finish, and a shorter adult height.
- Out-of-sequence signs. Pubic hair and body odour with no breast or testicular development. This points towards the adrenal glands rather than the normal pubertal axis.
- Signs on one axis only in a boy: pubic hair, growth and penile enlargement with small testes. This combination is important and should never be dismissed.
- Headaches, visual changes or neurological symptoms alongside pubertal change.
- Delay with a poor growth rate. Delayed puberty in a child who is also growing slowly is a different problem from delay in a child growing normally.
The things that are usually fine
Equally worth saying plainly, because these fill a lot of appointments and most resolve without treatment:
- Premature thelarche. Isolated breast development in a girl under two or three, with no growth spurt and no other signs. Often settles on its own; still worth one review to confirm nothing else is happening.
- Premature adrenarche. Body odour, mild pubic or underarm hair and slightly oily skin in a six- or seven-year-old, with normal growth and no breast or testicular change. Common, usually benign, occasionally a marker of insulin resistance later.
- Constitutional delay. The classic late bloomer, very often with a parent who tells the same story about themselves. Growth is slow but steady, bone age is behind, and adult height is usually fine. It can still be worth treating, because being fifteen and pre-pubertal is genuinely hard, and short courses of treatment are safe and effective.
- Gynaecomastia in adolescent boys. Breast tissue in mid-puberty affects a majority of boys to some degree and usually resolves within two years.
What an assessment involves
Nothing frightening, and usually nothing on the first day.
A history covering the sequence and timing of what you have noticed. Height and weight plotted against everything available from the past. An examination, done gently, with a parent present, and with the child’s permission and dignity taken seriously. In girls this often does not require a genital examination at all.
If investigation is warranted, it is typically an X-ray of the left hand and wrist for bone age, some baseline hormone tests, occasionally a stimulation test, an ultrasound, and in specific situations an MRI of the pituitary.
Talking to your child about it
Two things help more than anything else.
Tell them what is happening in their body before it happens, in ordinary words, and more than once. And separate the biology from the timing: there is nothing wrong with a body that starts early or late, and nothing wrong with the child living in it.
From about eleven onwards I ask for a few minutes alone with the young person at every appointment. It is not to exclude parents; it is because adolescents ask better questions when there is nobody in the room whose face they are watching.
General information only. If any of the patterns above describe your child, ask your paediatrician for a paediatric endocrinology opinion.