Breasts usually start to develop around the age of 9 to 11, but it’s normal for them to start earlier or later.
If a girl’s breasts start to develop at a younger age, this doesn’t mean she’ll have bigger breasts than someone who starts to develop later. The rate at which breasts grow is different for everyone.
How breasts start to develop
When breasts start to develop, a small bump called a breast bud grows under the nipple and areola (the darker area of skin around the nipple).
The breasts get bigger and rounder as the fatty tissue and milk-producing glands inside the breasts continue to grow. The areola also gets bigger and darker and the nipples may stick out.
By the age of 17, a girl’s breasts will usually be fully developed, although this may take a bit longer.
You’ll probably notice that you and your friends grow in different ways. One girl’s breasts may start to develop first, but her friend may get her period earlier. Bodies don’t develop in any set order and everyone’s different.
Aching, itching or tender breasts
As the breast buds grow, you may notice tingling, aching or itching in your chest, and your nipples may swell or become tender. This is all normal.
After your periods begin, the changing hormones may make the breasts feel tender, painful or sore a week or so just before your period starts.
Are my breasts normal?
It's common to worry about whether your breasts are normal. But normal breasts come in different sizes and shapes and everyone's breasts are different. Find out more about normal breasts and nipples.
Can I change the way my breasts develop?
There’s nothing you can do to speed up or slow down breast development.
Creams and pills
Adverts for creams and pills often claim that they can make breasts bigger or smaller. Such creams and pills don’t usually make any difference to breast size – even if there’s a slight change in size it’s unlikely to last.
Massaging the breasts won’t affect their size. Massaging too hard might even hurt the breasts or irritate the skin and nipples.
Breasts are mainly made up of fatty tissue rather than muscle, so exercise won’t affect breast development. However, exercise in general will help keep the pectoral muscles behind the breast in shape, as well as help toning the body.
Gaining or losing weight
Losing or putting on weight may affect breast size, but doesn’t always.
Girls naturally put on weight during puberty. It’s normal and essential to have body fat, so this is nothing to worry about. Because breasts contain fatty tissue, gaining weight may increase the size of the breasts, and losing weight may make the breasts a bit smaller.
Eating fatty foods or drinking lots of milk won’t affect breast development.
Sleeping on your front
Sleeping on your front won’t affect how your breasts develop or make them smaller. If your breasts are feeling sore you might find it more comfortable to sleep on your back or side.
Wearing a bra to sleep in
Whether you wear a bra to sleep in is a personal choice – most people don’t, but it won’t affect breast development. If you do sleep in a bra, make sure it’s comfortable and not too tight.
Cosmetic breast surgery is the only way to alter breast size – through either a breast enlargement with implants or breast reduction.
Breast enlargement or reduction surgery is available only to people over the age of 18. Surgery has potential risks and side effects – for example scar tissue and infection, and losing the ability to breastfeed.