Breast development and natural changes

A note on terms:

Breast cancer can affect anybody, and everybody is welcome in CoppaFeel!’s community. We’re actively inclusive in our language and we ask people how they want to be described. 

The word ‘chest’ is inclusive of all bodies and genders. When we need to be clinically accurate we use the word ‘breast’. You might prefer to call your chest something else, and that’s ok!

When we say breasts, we mean the part of your body from your rib cage up to your collarbone and armpits, including your nipples. This is where everyone has breast tissue, and people of all genders can get breast cancer. We often use the words ‘breasts’ and ‘chest’ in our breast cancer information. 

The more you get to know your chest, the more you will become familiar with natural changes that can happen. All bodies are different, and you are the expert on what is normal for you. It is important to pay attention to any changes to your chest. If you notice any changes you are worried about, speak to your GP.

Why do breasts change?

There are lots of harmless reasons your breasts, chest or pec can change naturally. This can be due to ageing like puberty which affects everyone. Changes can also occur due to your period, pregnancy and more.

How will my breasts change during puberty?

Breasts usually develop between the ages of 9 and 16, however, it can also happen earlier or later than this. Breasts are usually fully developed by the time you reach 17, however, if they’re a little later to develop there’s no need to worry.

Your breasts can change in a few ways during puberty:

• Increase in size (due to fatty tissue development and milk-producing glands).
• Breast buds (Small nipples under the breast and areola).
• Grow rounder.
• Areola (area around the nipple) gets darker and bigger.
• Nipples can become firmer.

You may notice some irritating symptoms when your breasts grow. They can:

• Ache.
• Itch.
• Feel tingly.
• Swell
• Become more sensitive.

There’s no need to worry if you notice these symptoms during puberty, however, if you’re worried you can always speak to your GP.

It’s also completely normal to gain some weight during puberty, this is because your body changes. When this happens, it can also affect your breasts. It also isn’t uncommon to grow some hairs around your nipple, for stretch marks to appear, or for one breast to develop more quickly than the other.

If you would like to know more about puberty, our friends at Brook are health and wellbeing experts for young people.

What’re the 5 stages of breast development?

There are five stages of breast development during puberty:

1. The pre-pubertal stage: Your breasts won’t have developed, although your nipple and areola (area around the nipple) may be slightly raised.
2. The beginning of breast development: Breast buds (small lumps around the nipple) begin to appear, the nipples and areola begin to darken.
3. Breasts and breast tissue continue to grow, becoming larger and rounder.
4. Your nipple and areola become more erect and elevated, forming a second mound above the breast. 
5. Your breasts reach their full adult size and shape, and only your nipple is raised above the breast.

What are breast buds?

Breast buds are one of the first signs of puberty and breast development in girls. They’re small lumps that grow under the nipple. They’re completely normal, however can be tender. They may also make the areola (dark area around the nipple) appear raised and puffy.

How can I tell if a change is because of puberty or a sign of breast cancer?

It’s important to get to know your own body, and what is normal for you. We encourage people to check their breasts, chest and pecs every month. Some lumps are perfectly normal, but if you get a new lump or a lump comes back you should contact your GP.

Is it normal to have two different sized breasts?

It’s perfectly normal to have breasts of different sizes or shape (breast asymmetry). In fact, it’s actually quite common for the shape and size of each breast to differ even once they’re fully developed.

What’s the normal breast size?

There is no ‘normal’ size, we are all one of a kind! Some people have one breast smaller than the other. Our bodies are always changing, and our chests will change too.

When do breasts stop growing?

The age your breasts start to develop, as well as how long they take to develop, depends on the individual. Breast development can be affected by lots of things, including genetics, hormones and lifestyle choices.

Typically, breasts take between 2 and 5 years to fully develop once they start. They’re usually fully developed by your late teens, although it isn’t uncommon for them to continue developing until the early 20s.

How will periods affect my breasts?

Menstruation (monthly periods) can also cause your breasts to naturally change as part of your monthly cycle. This is due to your hormone levels fluctuating. Your periods can cause your breasts to:

• Become sensitive, including the nipples.
• Swell.
• Feel full, heavy and painful.
• Grow lumps.

These changes are usually nothing for you to worry about, however, you can always contact your GP if you like.

Breasts come in all shapes and sizes, and they will change throughout your life. You should also keep an eye on any breast lumps that appear. Some breast lumps are perfectly normal, but if you get a new lump or an old lump comes back, contact your GP. It is important to get to know your normal monthly rhythm, so you notice any unusual changes quickly.

Even if you experience breast pain during your periods (cyclical pain), this usually isn’t anything to worry about. Breast pain on its own is rarely a sign of breast cancer.

Is it normal for your chest to hurt when you’re on your period?

It’s normal for your chest to feel tender, sore or swollen around the time of your period. Get to know what is normal for you around the time of your period.  

We suggest checking around the same time of the month, every month. If you notice any constant, unusual pain speak to your GP. 

How will my breasts change during pregnancy and breastfeeding?

Your breasts will change during pregnancy and breastfeeding. During pregnancy, your breasts will naturally prepare your body for breastfeeding. These changes include:

• Changes in size or shape.
• Changes in skin colour.
• Increased sensitivity.
• Visible veins.

It is important that you keep checking your chest during pregnancy. This is to help you get to know the natural changes that come and go. Breast cancer can happen during pregnancy and when you’re breastfeeding. If you are worried about any breast changes, talk to your GP or midwife.