Mismatched breasts

Dear Alice,

This has been bothering me for a while, but I'm too embarrassed to mention it to anyone. Is it common to have breasts that are different sizes? There's almost a cup size difference between my breasts. I'm almost eighteen, and I don't know if they'll "even out" as I get older, or not, or if this is something to worry about.

Dear Reader,

Breast assured, chest asymmetry is common and usually benign! Breast size and shape are unique to each breast-owner, and each breast can have its own distinct attributes. Some people's breasts don’t fill an A cup while others exceed a DD; one breast may be firm while the other sags; some are smooth under the skin and others are more lumpy. There might be differences in nipple-size or appearance, and some folks have one inverted nipple, while the other sticks out. While it’s likely that your different sized breasts aren’t a cause for concern, there are some options for you to explore, if you want a more symmetrical look. It also might help to know that breasts go through typical changes across the lifespan. 

Believe it or not, breasts actually start to form in the womb! It’s only once puberty-driven hormones hit, however, that the breast buds enlarge. If you’ve just started developing breasts, one may grow faster than the other, so it can be difficult to know the degree of asymmetry until around age 20. The breast sizes may even out by the end of puberty or they may not — 25 percent of adults with breasts have some form of asymmetry. For those assigned female at birth, the fun doesn’t stop when puberty ends — even after breasts reach their full development, hormonal fluctuations can change their shape and appearance across the lifespan. For example, while menstruating, breasts become fuller and more tender; for those who are pregnant and nursing, they generally enlarge a great deal; and, for those who experience menopause, breasts may have more lumps.

There’s no need to get your bra in a twist over different sized boobs, and plenty of people rock their unique pair of breasts proudly! That being said, if you’re feeling especially self-conscious or concerned, there are a couple of actions you could consider taking. If you wear a bra, you may try wearing a bra with extra padding or an insert on one side, or, if you still have a pronounced (and distressing) difference after puberty, surgery is also an option.

Generally, differences between breast size and shape are nothing to worry about, but in some cases they can indicate existing conditions or risk factors. It’s possible that asymmetry could be caused by an injury to the breast before puberty or an abnormal rib cage or spinal structure. Studies have also found that there’s a slight correlation between a breast asymmetry ratio over 20 percent and breast cancer risk.

Since there are many individual differences in breast size and shape, it’s good to have an understanding of what’s "normal" for you. Becoming familiar with your breasts will help you notice any changes in the tissue that may be a cause for concern. If you detect anything different from the usual, it’s best to consult with your health care provider. For information on screening for early breast cancer detection, check out the American Cancer Association’s recommendations.

Last updated Apr 05, 2019
Originally published Sep 22, 2000

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