Puberty is the set of changes that turn a child's body into an adult one, and it happens over several years rather than all at once. It starts at a different age for different people, and starting earlier or later than your friends does not mean anything is wrong. This page is health information for learning, and a doctor or a trusted adult can help you with anything that worries you.

It happens in an order, and the order is more useful than the age

For most girls the changes come in roughly the same order, even though the ages vary a lot.

Usually the first change is that the breasts begin to develop. A small, firm, sometimes tender lump forms under one nipple, then the other. It is very common for one side to start before the other, and for it to feel sore for a while.

After that, hair starts to grow on the pubic area (the skin over the pubic bone, in front) and later under the arms. Around the same time you get taller quickly — the growth spurt — and your feet and hands often grow before the rest of you catches up.

Periods usually come near the end of this sequence, roughly two years or so after the breasts start developing. That is why what a period actually is is worth reading before yours arrives rather than after.

The ages are wide, and that is normal

In girls, the first signs of puberty most often appear somewhere between about 8 and 13 years old [NHS; NICHD]. That is a five-year window. Two people the same age can be at completely different points and both be fine.

There is no target to hit and no stage you are supposed to be at. Bodies are different sizes and shapes at every stage, and none of that tells you whether puberty is going the way it should.

Other things that change, and get talked about less

Discharge. Some months or years before periods start, you may notice a small amount of clear or whitish fluid in your underwear. This is normal. It is how the vagina (the tube inside) keeps itself clean.

Skin and hair. Skin often gets oilier and spots are common. Hair may get greasier faster.

Sweat and smell. Sweat glands become more active, so you may notice body odour where you did not before.

Mood and sleep. Feeling more up and down, and wanting to sleep later, are both ordinary parts of this age.

Your vulva. The vulva (the outside parts) also changes shape and colour. There is no standard one.

Any word here you have not met before is explained in the glossary.

When to see a doctor

Almost everything above is ordinary and needs nothing done about it. There are a few things where you or a trusted adult can ask a doctor to take a look — not because something is wrong, but because a doctor can check and usually reassure you.

You or a trusted adult can arrange to see a doctor if:

• there are no signs of puberty at all by about 13 [NHS]
• puberty seems to be starting very early, before about 8 [NHS]
• one breast is growing and the other has not started at all after a long time, or there is a lump that feels hard, does not move, or is getting bigger
• a change is painful in a way that does not settle
• you feel worried about it, which is a good enough reason on its own

Asking is not the same as something being wrong. Most of the time the answer is that everything is going as it should, and hearing that from a doctor is worth the appointment.

If any of this is difficult to bring up at home, there are other adults who can help, and it is fine to start there instead. You can also read about getting ready for your first period whenever you want to — you do not have to wait until something changes.