Technically, they don't. It's not age that makes your breast get bigger. It's weight gain—and people happen to gain weight as they age.
You may also notice that your breasts are a different size or shape than they were when you were younger. Changes to your breasts are a normal part of aging. Changes in firmness or size are very common, especially after menopause.
Your breasts will change throughout your lifespan. In your 30s, breasts still retain much of their elasticity and firmness. However, it is not uncommon for some women to become prone to fibrocystic developments after this point.
Boob growth with age is normal, with one in five women experiencing a noticeable increase, with many ballooning by two sizes or more. Once more, your shifting hormones are responsible for this bodily change.
It can happen during puberty, pregnancy or from taking medication. In some cases, it occurs spontaneously and for no reason. Gigantomastia is also referred to as macromastia. However, macromastia is usually defined as excess breast tissue that weighs less than 5 pounds.
As females get older, their bodies start to produce less of the reproductive hormone estrogen than before. Estrogen stimulates the growth of breast tissue, while low levels of this hormone cause the mammary glands to shrink.
During perimenopause, the hormonal fluctuations are more dramatic. It is also common for breasts to get bigger or smaller or to change in shape during this period.
As you reach the age of 40 years and approach perimenopause, hormonal changes will cause changes to your breasts. Besides noting changes in your breasts' size, shape, and elasticity, you might also notice more bumps and lumps. Aging comes with an increased risk of breast cancer.
There's no specific age when your breasts will start to sag. It's common for some droop in your 40s and beyond, but many women experience saggy breasts earlier. If you're lucky enough to escape the droop in your 30s and 40s, you'll most likely notice changes in elasticity and fullness as menopause approaches.
In general, breast development begins between the ages of 8 and 13. A girl's breasts are typically fully developed by age 17 or 18, however in some cases they can continue to grow into her early twenties.
The transition through menopause may cause several changes to the breasts, potentially affecting their shape, sagginess and texture. They might even noticeably increase in size, with many women going up by two bra sizes or more.
"If you don't wear a bra, your breasts will sag," says Dr. Ross. "If there's a lack of proper, long-term support, breast tissue will stretch and become saggy, regardless of breast size." Still, both experts agree that multiple factors play into if and when sagging (technical term: "ptosis") occurs, bra-wearing aside.
Unfortunately, since breasts are not made up of muscles, it is not possible to firm up breast tissue with exercise. Breast lift surgery is the only way to bring back the original shape of the breasts. However, you can take certain measures to improve the overall appearance of your breasts.
Dr. Blake says wearing a bra doesn't prevent your breasts from sagging and not wearing one doesn't cause your breasts to sag. “Wearing a bra doesn't affect the risk of breast sagging, or what is called 'breast ptosis,'” she says. It also won't impact the shape of your breasts.
This is supported by evidence showing that women with larger breasts tend to have higher estrogen levels; breast size may therefore serve as an indicator of potential fertility. However, breasts become less firm with age and parity, and breast shape could thus also serve as a marker of residual fertility.
While it's really difficult to precisely determine the standard breast size in the U.S. (or anywhere in the world, for that matter), we do know that the average breast size in America is a 34DD.
The breasts get bigger and rounder as the fatty tissue and milk-producing glands inside the breasts continue to grow. The areola also gets bigger and darker and the nipples may stick out. By the age of 17, a girl's breasts will usually be fully developed, although this may take a bit longer.