What Actually Determines Breast Size?

Have you ever wondered why some women are born with naturally large breasts while others stay small? While genetics definitely play a role, there are other factors that come into play. And if you think about it, most body parts, such as hands, feet, arms, legs, eyes, etc. stop growing at one point, but breasts are a different story. A woman’s breasts will usually change size and shape throughout her life.

What factors determine breast size and shape? Here’s a list of the biggest culprits that determine the size of a woman’s breasts.

  • Family History: Your genetics determine your hair, eye, and skin color, and how tall you are. They also impact your breast size. If you have an A-cup, it’s very likely that someone in your family also has or had an A-cup. Think about your mother, your aunts, and your grandmother. Did they have small breasts in their youth?
  • Weight: Some women have more fat tissue in their breasts than supportive tissue and vice-versa. If your breasts have a higher concentration of supportive tissue than fat, your breasts may not grow much when you gain weight. On the other hand, if you have more fat tissue, they may grow significantly when you gain weight.
  • Exercise Routine: If you start strength training and you do chest exercises, this may grow your pectoral muscles, causing your boobs to push out a little bit and look perkier than usual.
  • Menstruation: A woman’s menstrual cycle can have distinct effects on the size, shape, and texture of her breasts. As you get closer to your period, an increase in progesterone production can cause swelling and even soreness, prompting women to wonder if it’s them or if their boobs got a bit bigger.
  • Birth Control: Hormonal birth control, such as the pill, hormonal IUD, and the shot can cause edema (water retention), leading to a temporary increase in breast size.
  • Pregnancy: Breasts change during pregnancy and postpartum; it’s a fact of life. It’s common for even an A-cup to grow several cup sizes during pregnancy due to increases in progesterone. If you decide to breastfeed, they can continue to swell after the baby is born, but they should go back to their normal size (not necessarily their old shape) about six months after you stop nursing.
  • Age: Even if you never have children, your breasts during menopause will not look the same as they did at 18. When you enter menopause, you’ll go through hormonal changes, which will affect the size and shape of your breasts. When the body produces less estrogen, the connective tissue in women’s breasts loses elasticity. All breasts eventually become less perky as women age, and it’s usually due to a decrease in skin elasticity and stretched ligaments.

Unhappy with your breast size or shape? Contact our office to meet with our Board-Certified Plastic Surgeon, Dr. Yuly Gorodisky to explore your options.