Know the Reasons Why Your Breasts Are Different in Size

A woman's breasts are very complex. They are designed by nature to provide sustenance for the infant and child, and can usually do this reliably for many years. The breasts are created of many parts, including lymph vessels, lymph nodes, fatty areas, breast tissue, connective tissue, muscle, milk ducts, and so much more.

Ignore all of these elements of the breasts, as well as their natural function, the breasts come in a variety of shapes and sizes. However, when a woman realizes that she has one breast bigger, it can be cause for alarm. What does that mean? Does it mean that she has a higher risk of breast cancer? Does it mean she won't be able to feed her baby appropriately?

One Breast Bigger Than the Other: Is It a Problem?

The good news is that many women realize at some point that they have one breast bigger. This is usually very normal. In fact, most women have different sizes for other things too – for instance, your ring size might be different from one hand to another, or you might have different sized feet.

And if you find one breast smaller than the other in newborn babies, this is usually caused by the hormones in the mother before birth, and will resolve as soon as the baby's own body grows. This usually happens within a few days.

What's more, having one breast bigger than the other is very common during puberty, as your body isn't guaranteed to grow at the same rate on both sides. However, the breasts do settle down into a similar size by the time you are an adult. If the breasts continue to be different sizes, there might be a few reasons:

1.  There Are Hormone Changes

The flow of hormones through your body affects everything, including breast size. This happens during your menstrual cycle, pregnancy, menopause, puberty, and while breastfeeding. It is also very common in women who are taking hormone replacement therapy or certain hormonal birth control methods. Usually, you don't need to worry a lot in this condition.

2.  There Are Some Problems

However, sometimes the swelling of one breast can be caused by a variety of issues, such as an abscess, a tumor, a cyst, or other problems. Here is a list what might make one breast bigger than the other:



Trauma or Injury

When the breast is injured, blood pools underneath the injured area. There might also be an area of fatty tissue that develops a hard lump and swells.


Mastitis is an infection in a milk duct. There might also be an abscess, cellulitis, or other inflammation of the skin of the breast.


Also known as a "breast mouse," this is a smooth swelling that can be moved around underneath the breast tissue. It is usually benign.

Fibrocystic Breast Disease

This results in hard lumps in the breasts. Though the bumps can be painful and unsightly, there is no fear of cancer.

Breast Cancer

Though swelling is not the most common symptom, it is definitely worth having your breasts checked for cancer if you notice one breast bigger than the other.


This is an area of fatty tissue in the breast that can make it appear swollen and larger than the other.


Cysts can occur anywhere in the body. They are tiny sacs filled with fluid. They are most commonly found in the breasts right before a woman starts her period, and might vanish between periods.


Problems with implants can feel as though there is a hard lump underneath the tissue.

Lymphatic Obstruction

This happens when a lymph node or lymphatic vessel becomes clogged, resulting in an obstruction that prevents the flow of lymph fluid through the breast.

Remember that having one breast bigger than the other might not be a sign of anything wrong. It could simply be the way your body is made. In case you have concerns, speak with your doctor to ensure that there are no underlying conditions that might be causing the issue. Or you can learn from the video below for breast self-check: 

All in all, having a discrepancy in breast size from one to the other doesn't mean that you are at any higher risk of any problems, such as cancer. The different breast sizes shouldn't cause a problem for you in any way, including if you try to breastfeed an infant. The only issue might be that your typical bra sizing doesn't work for you, and you might need to invest in custom-made bras if the condition is chronic.