Breast development: Stages and how to spot growth signs - Flo (2024)

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Your teen years are full of pretty notable firsts — your first crush, maybe your first kiss, and your first period. This can all be very exciting, but the emotional and physical changes that make up puberty might leave you with a few questions — namely, what’s going on with your boobs?

One of the earliest changes you might have noticed is that your breasts have started to grow and change shape. For many people, puberty begins between the ages of 8 and 13 years old, but your breasts continue to develop well into adulthood. While this is to be expected and is something to be celebrated (boobs are great, after all), it’s natural to feel self-conscious at times about the way your body is changing. You might find yourself looking at your friends and peers and wondering if you’re “normal,” for example.

To reassure you, a Flo expert shares the lowdown on how your breasts might change during puberty — including what is considered to be early or late development and how to choose your first bra.

What are the breast development stages during puberty?

The changes you experience during puberty might feel overwhelming and hard to track. Between your period starting and hair growing in new places, it’s common to feel like you’re living in a new, slightly unpredictable body. However, knowledge is power, and understanding what might happen and when may help you feel more in control.

So, first up, what even is puberty? It might come as no surprise that it has a lot to do with hormones. Puberty is triggered when the hormone center of your brain — known as the hypothalamus — releases hormones to start new processes. For example, follicle-stimulating hormones and luteinizing hormones act as a green light for your ovaries to start producing the sex hormone estrogen, which plays a role in breast development.

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Estrogen triggers fat to collect in the chest area around age 10. However, this can happen a little earlier, so you may notice changes between the ages of 8 and 12. This means, from that point onward, breast buds start to form under the nipple.

Breast buds are small, disc-shaped bumps that might cause your nipples to stick out. They might appear like raised bumps initially and feel slightly sore, itchy, or uncomfortable — all of this is perfectly normal. The area around your nipple, called your areola, may also start to grow and darken in color. This is also totally expected and nothing to worry about. It’s even a sign that you might be about to reach another big milestone. While they might not feel like they’re connected, breast buds tend to form around two years before your first period. So, if you start to notice your chest developing, you can prepare for your first menstrual bleed. To learn more about how your body may change during puberty, use an app like Flo.

Tanner stages in girls: Female breast development scale

When you think about your breasts developing, you might just imagine them getting bigger, but there’s a little more to it than that. While you might notice growth, your boobs can also change shape, and your nipple may change too. To understand this development, you can review the sexual maturity rating or the five Tanner stages — named after Professor James M. Tanner, a child development expert who was the first to identify and label the visible stages of puberty.

Signs your breasts are growing

You might have been waiting to spot the first signs of puberty, and you may be able to feel new developments before you see any differences.

“The breast area can be tender or sore or itchy during breast growth,” says Dr. Sara Ritchie, assistant professor of pediatrics at the Medical University of South Carolina, US. This is all totally normal and nothing to worry about. You might also see some changes in the skin around your boobs as they grow. Some people develop stretch marks on their breasts, which may fade over time. If you feel at all self-conscious about stretch marks, remember that they’re totally normal, lots of people have them, and they’re just your body’s way of helping you grow into the adult you’re going to be.

Are there nonphysical signs that breasts could be growing?

You’ll probably already be aware that puberty can affect how you feel as well as how you look. Mood changes are a symptom that many of us experience throughout our teen years and into adulthood. Again, this comes down to your hormones. While mood swings aren’t a direct sign that your breasts are developing, they are a big indicator that you’ve hit puberty. To learn more about how your hormones can impact your mood during puberty, you can use an app like Flo.

What do teen breasts look like?

It can take a while to get your head around the changes in the way your body looks and feels. Many of us don’t have anyone to compare our own to, which means there’s often curiosity around what breasts are supposed to look like and whether yours are “normal.”

The answer to this question is pretty straightforward. When it comes to the way boobs look, there’s no such thing as normal. They’re all awesome! Your breasts will grow, change in shape, and change size throughout your teen years, so try to embrace them however they look.

“It can take about four years for the breasts to fully develop,” says Dr. Ritchie. “The size may be uneven [but may balance] out over time. Many adults have slightly different-sized breasts,” Dr. Ritchie adds. In fact, around one in four adults have boobs that aren’t exactly the same size and shape, so if this is the case for you, remember it’s very typical.

Your breasts will continue to develop until you’re around 17 or 18 years old, but that’s not the end of their journey. Many fully grown adults will tell you that their boobs have changed throughout adulthood. Keep reading to find out how.

What is considered to be late or early development?

As we mentioned, most people start puberty between the ages of 8 and 13 years old. And, generally speaking, the earlier you start, the earlier you’ll finish. But puberty can begin at different times for different people. So, while we know it can feel worrying if you’re not at the same stage as your friends (whether you’re the pioneering pal who is the first to wear a bra or if you’re still waiting for that day to come), try not to worry. Your body is just going at its own pace.

Some people start puberty earlier than average — before the age of 8 — and this is known as precocious puberty. On the other hand, delayed puberty is when things are happening more gradually, and you haven’t started to develop breast buds by the age of 13.

If you’re worried about how quickly or slowly you’re developing, then speak to an adult you trust or your doctor. It’s very normal to have questions, and they’ll be able to walk you through what might be happening.

Can breasts continue growing into your 20s or 30s?

This might come as a little bit of a surprise to you, but your breasts don’t stop changing once you finish puberty. So let’s break this down. Your boobs might change size in your twenties, thirties, and beyond if you lose or gain weight. This is because your boobs are partially made up of fatty breast tissue. If you lose weight, then you may lose it from your chest.

Similarly, once you start your period each month, you’ll experience a rise and fall in the hormones estrogen and progesterone. This is in line with your menstrual cycle. During their period, many people report their breasts feeling different in texture — they might feel firmer or lumpy. You’ll know what’s normal for you, so if you’re ever worried about a change in the look or texture of your boobs, don’t be afraid to reach out to your doctor.

It might feel like a long way away, but pregnancy and breastfeeding are also big times of change for your body, including your breasts. When you’re expecting a baby, your body releases a hormone called prolactin. This encourages your breasts to start to produce milk, changing their size and look. Pretty amazing, right?

Can you have complications when your breasts are growing?

Feeling tingling, itchiness, or tenderness around your boobs can feel unfamiliar, but generally, most people move through their teen years without complications related to their breast growth. If you are worried, you can always speak to an adult that you trust and your doctor. It might be a part of your body that feels private, but don’t let that put you off — your doctor will be able to answer any of your questions and check for any changes. Remember, they’ve seen everything before!

It’s also totally normal to have mixed feelings or emotions relating to your body developing during puberty. These can range from excitement or curiosity to feeling anxious or upset. You might have mixed feelings for lots of reasons. One reason why some people feel conflicted as their body changes is that they no longer feel like their gender identity matches the sex they were assigned at birth — and that’s normal too. Gender dysphoria describes this unease that your biological sex and gender identity don’t match. If you’ve experienced any distress or anxiety surrounding how your body is changing, then don’t be afraid to speak to a trusted adult. This could be a family member, friend, or organizations like Trans Lifeline or Switchboard. Remember, you don’t have to navigate these feelings on your own.

When should you see a doctor?

While most people’s boobs change throughout their teens and adulthood without complication, there are some signs you can look out for that may suggest it could be helpful to speak to your doctor. New aches and pains can be worrying, but there’s no such thing as a silly question. These signs include:

• Severe pain, particularly if it’s just on one side
• Redness on the skin of the breasts
• Nipple discharge
• Lack of development by the time you are thirteen
• “Breast masses” or lumps in the breasts

How to choose a bra when you’re a teenager

When your boobs start to grow, you’ll likely be wondering when you can get your first bra. Buying your first bra might seem like a rite of passage and something everyone does. It’s really important to remember that there’s no right or wrong time to buy a bra. You’ll know how your body is changing, and a bra may help you feel more comfortable. But if you’re not ready yet and don’t want to wear one, that’s also totally fine.

Talking this through with an adult you feel comfortable with — whether it’s a friend or family member — before you go to the store might help you work through any nerves. It’s natural for the underwear section to feel like an unknown land, but take someone with you for moral support, and you’ll get familiar with the new world of bra shapes and cup sizes in no time. If going to the store feels embarrassing, then you can also shop for your first bra online. All you’ll need is a tape measure so you can figure out what size you’ll need.

Wearing the right bra size is really important, as it can support your boobs as they grow and may ease any discomfort you have. You’ll notice there are lots of different types of bras — from bralettes to underwire bras and sports bras. Each will feel different, and there’s no “right” style for a first bra, so explore what feels best for you.

Breast changes during puberty: The takeaway

Like most parts of puberty, breast development can feel sudden and unpredictable. It’s totally normal to have questions about what’s going on with your body, and so, hopefully, now you feel more informed.

The most important thing to remember is there’s no such thing as normal when it comes to boobs. They can be different sizes and shapes at different points in your life, as they’ll grow and change with you. So remember not to be hard on yourself, and instead, try to embrace the changes you’re going through as your body develops.