Why Do My Breasts Grow and Shrink?

By: Kate McCallum

Have you ever noticed that sometimes your breasts appear larger or smaller than usual? Throughout your life, you will probably notice changes in the size of your breasts - whether that be shrinkage or growth. Just like other parts of your body, it is entirely normal that your breasts change in shape, size and texture - they can even grow or shrink to different sizes! These changes can most likely be attributed to weight gain/loss, phases of your menstrual cycle or changes in your exercise regime. 

Ultimately, it is important to understand that these fluctuations are not a cause for worry, but are instead a common experience for many girls. 

your menstrual cycle

A common misconception is that you will only experience symptoms of your menstrual cycle when you are on your period. Instead, your period marks the beginning of your monthly menstrual cycle, during which your body will experience many symptoms unique to each week of the cycle. 

Your breast size, shape and texture can change dramatically throughout the course of your menstrual cycle. During the first half of the cycle, your body will secrete a hormone called estrogen, which stimulates ovulation and activates milk ducts in your breasts, which will not change breast size, but may cause the breasts to appear lumpier than usual. If you notice this lumpiness in your breasts on a monthly basis, not to worry - it is a normal and healthy feature of the reproductive system. 

During the second half of the cycle, as you approach your period, your body will begin to secrete progesterone, which stimulates the formation of milk glands, which may cause your breasts to swell and/or feel soreness. Periodic changes in your breast size are fairly predictable, and can often be explained by hormone fluctuations throughout the menstrual cycle. If you notice swelling or tenderness in your breasts, think about when you last had your period - it is most likely approaching in the next week and could explain this discomfort. 

A helpful tip to ease breast soreness and swelling during your period is to wear a more supportive bra, and/or exercise more regularly. Apricotton’s Artemis Sports Bra is a perfect option for a supportive and sport-friendly bra to wear during these uncomfortable days of your menstrual cycle. The stretchy fabric and elastic waistband allows for your breasts to change in size, while remaining comfortable.

weight loss/gain

Research says that your breasts are composed of a complex network of connective and supportive tissues, milk glands and ducts, as well as fatty tissues. Every girl has a different ratio of connective, supportive and fatty tissues in their breasts, due to their genetic makeup. This creates a unique relationship between changes in breast sizes and weight gain/loss. If your breasts have a higher amount of fatty tissues compared to connective or supportive tissues, you will likely notice more drastic changes in your breasts as your weight changes. 

This change in breast size happens because fat cells expand as you gain weight, and shrink as you lose weight. That being said, you would need a large change in your overall weight to have a large impact on breast size. Research says that it would require a 20% gain or loss of your original weight to grow or shrink your breast size by an entire cup size. This means that you should not expect your breasts to vary drastically as your body experiences the weight fluctuations commonly associated with growth spurts during puberty.

However, if you're going through puberty right now it's natural for your breasts to grow a lot! If you're worried about outgrowing your bras, try our Cloud Bra, which is designed to not only grow with you, but with your underbust throughout weight fluctuations too!

exercise routine

While it is uncommon for your exercise routine to change the actual size of your breasts, it is possible for certain exercises to cause your breasts to appear larger or smaller. This is particularly true for exercises that build your pectoral muscles, such as weight lifting or pushups. The pectoral muscles are the four major muscles that sit behind your breast tissue, and as they grow, you may notice that your breasts sit further outwards, and appear to be larger and different in shape. 

All in all, there are so many different reasons that your breasts may change in size, but it is important to remember that these changes are healthy, and particularly common during the unpredictable years of puberty. Try to avoid judgement as your breasts evolve, and celebrate your body for all of its unique characteristics. 

If you have any questions or comments, contact Apricotton through our Instagram or send us an email at info@apricotton.co!

About the Author

Kate is a business student at Western University, who enjoys hiking and canoeing in her free time. As the oldest of three sisters, Kate has a passion for sharing advice, and helping girls build a sense of self-confidence.