No two people are perfectly identical – no matter what science fiction tries to tell you. Some people are born taller, others shorter, wider noses or ears that may stick out.

For women, their breasts can vary wildly. Some women are born with naturally large breasts, and others are small. It’s not always about size either; shape or symmetry can also vary in breasts.

“While all women have some breast asymmetry, some feel uncomfortable with their uneven shape,” writes Toronto Plastic Surgeons, a clinic offering Toronto breast augmentation in Canada. “[This Makes] it challenging to shop for bras and bathing suits.”

The changes don’t stop after puberty either; women’s breasts can change the size and shape throughout their life. But why is that? Here are a few factors as to what can change the appearance of women’s breasts in their lifetime.

Main Determining Factors Of Breast Size



Hereditary genetics directly contribute to many physical factors like eye color, skin color, height, weight, and breast size. Of course, genetics don’t guarantee women will have the same breasts as the other women in the family, but a woman coming from a family of prominent breasted women, for example, will be less likely to have small breasts.

Weight Changes

All breasts contain fatty tissue, and how much fatty tissue varies from person to person. Those with higher fat levels may notice a direct change in their breast sizes as they fluctuate weight. Like other parts of your body, gaining weight causes the fat to expand, making the breast heavier, and putting more pressure on the breast.

On the flip side, losing weight shrinks this fatty tissue which can make the breasts appear smaller. If the breasts were previously stretched from weight gain, they might begin to appear deflated or saggy. This is especially noticeable if the weight loss is extreme or happens quickly.

Minimal weight loss and weight gain will rarely impact breast size, especially on those who had less fatty tissue, to begin with.



Exercising can also contribute to breast size. Besides the changes associated with weight loss that comes from exercise, doing frequent chest exercises will build your pectoral muscles, which are located below your breast tissue. As these muscles tighten and grow, they can lift and push out the breasts to appear more perky, firm, and large. It’s relevant to note the breast itself isn’t changing shape or size from the exercise; instead, the muscles under and around them are.

Menstrual Cycles

The menstrual cycle often brings significant hormonal changes to a woman’s body, including to their breasts. The size, shape, and texture of breasts can all be affected during a woman’s period. During the second half of a menstrual cycle, the body produces a hormone known as progesterone, stimulating the milk glands. This causes the glands to swell and the breasts along with it. The expanded glands may also cause the breast to feel “lumpier” and have harder spots along with it. Women can often notice tenderness and soreness in their breasts during this time. These effects are temporary, and the breasts will revert to normal once your period is over.

Other Breast Changing Factors

Birth Control: Birth control can cause water retention, leading to temporary increases in breast size.

Pregnancy: It is common for women to grow several cup sizes during pregnancy, even more than during their cycle, due to higher progesterone production.


Breastfeeding: When breastfeeding, the breasts will continue to grow but decrease a few months after stopping nursing.

Age: As menopause begins, women’s hormones begin to change drastically. One side effect of this is changing the size and shape of the breast. Less estrogen in the body means breasts begin to lose elasticity and appear to sag.

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