6 Surprising Facts About Your Breasts

Your breasts are pretty remarkable—and you may not know everything they can do.

Medically reviewed in July 2022

Updated on July 6, 2022

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Your breasts are responsible for incredible things. But we bet you don’t know everything they can do.

First, let’s start with the obvious. It’s remarkable that our breasts have the ability to make milk and feed our babies, says Kristi Weaver, DO, OBGYN at Overland Park Regional Medical Center in Kansas. “I see it every day, and I still almost don't believe it,” says Dr. Weaver. 

In addition to providing nourishment for your newborn, here are six more amazing facts about your breasts.

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They’re not identical

If your bra seems tighter on one side of your chest, you’re not imagining things—many women have one breast that’s larger than the other, says Weaver. On average, the left breast is more likely to be bigger than the right.

Genetics and hormonal changes such as puberty, pregnancy, menstrual cycle fluctuations, and menopause are likely contributors to size variations. A traumatic injury to the chest and non-cancerous tumors called fibroadenomas can also lead to asymmetry. 

Though it’s totally normal to have uneven breasts, if you notice one is suddenly a different size than the other—and you didn’t see it before—reach out to a healthcare provider (HCP). Developing breast asymmetry is linked to breast cancer.

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Nipples can trigger an orgasm

A little nipple stimulation may send you on the fast track to orgasm. “Interestingly, nipple stimulation activates the same region of the brain that is activated by clitoral and vaginal touch,” says Weaver. This area of the brain is known as the genital sensory cortex, and it’s activated by the stimulation of the clitoris, cervix, and vagina, too.

While only a small percentage of women are able to orgasm with nipple stimulation alone, it can certainly enhance a genital orgasm, Weaver adds. Nipple stimulation can include kissing, touching, and sucking, but what feels good is different for everyone. If you’re curious, talk to your partner about experimenting in bed.

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Your breasts are constantly changing

It’s normal for your breast size and density to fluctuate as you age. “When we're young, we have more glandular tissue in our breasts and as we age, it changes to more fatty tissue,” says Weaver.

Pregnancy, breastfeeding, and weight fluctuations cause density changes and sagging, too. “When you have too much weight loss or gain, the glandular tissue in your breast is replaced with fatty tissue. It’s difficult to regain glandular tissue,” says Weaver. Sun exposure and smoking also cause damage to the outer tissue of the breasts.

Want to help potentially slow sagging? Quit smoking, stay out of the sun, and maintain a healthy weight, recommends Weaver.

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The color and size of your nipple can grow or change

There’s no “normal” when it comes to nipple and areola color and size. “Some women have very small nipples and small areolar tissue, while some women have very large areolas,” says Weaver.

Why? It probably has a lot to do with your hormones. You may notice an increase in your nipple and areola size and color after puberty or when you’re pregnant.

“Huge amounts of estrogen and progesterone during pregnancy increase the size of that tissue and causes some darkening of the area,” says Weaver. The color change is really thought to help infants better identify the nipple from the surrounding breast tissue so they can feed better, adds Weaver.

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Breastfeeding can be good for mom, too

Just like babies, moms who breastfeed may reap benefits. Breastfeeding helps decrease the size of the uterus. “Lactation, or milk letdown, is actually stimulated by the same hormone in the brain, oxytocin, that causes uterine contraction,” explains Weaver. “When we breastfeed our babies, the oxytocin hormone is released and the uterus contracts down.”

Breastfeeding may boost cardiovascular health, too. One large study involving nearly 290,000 Chinese women found that mothers who nursed their babies lowered their own risk of having a heart attack or stroke by about 10 percent compared to moms who never breastfed. Published in the Journal of the American Heart Association in 2017, the study also found that the longer women breastfed, the lower their risk of heart disease.

That's not all: Breastfeeding can also help reduce your risk of postpartum hemorrhage and some kinds of breast cancer, as well as breast and ovarian cancer in the long term. People who breastfeed may find themselves hungrier, too, as nursing can burn about 500 calories per day.

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Eidlitz-Markus T, Mukamel M, et al. Breast asymmetry during adolescence: physiologic and non-physiologic causes. Israel Medical Association Journal. 2010 Apr;12(4):203-6. 
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