Puberty: what changes and when

Small, tender lumps under the nipples can be breast buds. They are an early part of breast growth, and they develop slowly over several years. Your first period doesn’t have to come at the same time as your first breast changes.

Changes before the first period

During puberty you grow taller and your body shape changes. Your hips may get wider, and you may notice more fat around your bottom, hips and thighs. Hair can grow under your arms and around your vulva, and it gets thicker over time.

You may sweat more or notice a stronger body smell. Your skin can get oilier, with spots or acne. You can ask about these changes too, not only about periods.

Breast buds can be tender. Breasts may grow quite fast or stay small, and they develop over time. How someone else looks can’t tell you when your own body will change.

Hormones send the signals behind these changes. During puberty, the pituitary gland in the brain makes FSH (follicle-stimulating hormone). This helps tell the ovaries to make oestrogen. Oestrogen plays a part in breast growth and in starting periods. So the changes are linked, even if you notice them at different times. If you are worried about the timing, ask about the changes you have seen.

Discharge can arrive first

Clear or whitish fluid in your underwear can appear before your first period. This is vaginal discharge: fluid or mucus that helps keep the vagina moist and clean. It isn’t the same as period blood.

Get advice if your discharge changes in smell, colour or texture, or comes with itching or soreness. In the UK, contact NHS 111. In the US and elsewhere, contact your doctor. Describe what changed rather than trying to work out from its look whether it’s an infection.

When changes can start

Different guides give different age ranges. The NHS says puberty in children usually starts between the ages of 8 and 14 years old. ACOG’s guide for girls says changes can start as early as age 8 or as late as 13. These guides describe different groups, and neither gives an exact date for a first period.

ACOG says periods usually start about 2 to 3 years after breasts begin to develop. This is only a guide, so it can’t tell you exactly when your first period will come. For a parent or carer, it’s a good reason to talk about periods before any bleeding starts.

Changing hormones can also bring stronger feelings and a wish for more privacy. You can ask an adult you trust for help and still ask them to give you space. If you are supporting a young person, ask what they want to know and use words they understand.

It can help to get ready for the conversation. Write down the changes you’ve noticed and roughly when they started. Then add the question that worries you most. A parent can help with practical things without doing all the talking for you. Ask for answers in plain language, and say if you’d rather talk about something in private.

When to book an appointment

Book a GP appointment (UK), or see your doctor or paediatrician (US and elsewhere), if puberty starts before age 8, breasts have not started to develop by age 13, or you are worried about the timing. The advice about breasts applies even if pubic or underarm hair has appeared.

Book a GP appointment (UK), or see your doctor or paediatrician (US and elsewhere), if your first period has not come by age 15. Do the same if 3 years have passed since your breasts began to develop and you have not had a first period. The NHS uses age 15 as the point to get checked. ACOG also advises a check if there is no first period 3 years after breasts begin to develop.

A clinician may suggest blood tests to check hormones and, if needed, scans. Timing sometimes runs in families. Food and nutrition, long-term health conditions and hormone problems can also play a part. Ask what each test is looking for and when you will talk about the result.