Uneven boobs: Why is one boob bigger than the other?

Why are my boobs uneven?

Have you ever cupped your boobs and thought hmm, why is one boob bigger than the other? 

Well to reassure you, most women have uneven boobs to some degree. They can vary slightly in shape, position and size. Boobs aren’t meant to be twins but more like sisters. No two breasts look the same just like no two vaginas look the same. 

Uneven boobs or breast asymmetry to a slight degree is usually not a reason to worry. However, sometimes if the breast asymmetry is quite large, it can affect self-image and self-esteem.  

Reasons for breast asymmetry 

Breastfeeding 

Uneven boobs and breastfeeding can go hand in hand. As your body produces milk supply, it causes your breast to swell. If you breastfeed from one breast a little more than the other, it might give the image that the breast is asymmetrical. This cause of uneven boobs does not tend to require treatment and should return to their normal shape and size once you have finished breastfeeding. 

Scoliosis 

1 in 120 adults in the UK have a spine that curves sideways. This is referred to as scoliosis and can vary in severity. Scoliosis is a known cause of uneven boobs. As the spine curves it is thought that the asymmetry of the breasts are enhanced. Interestingly, a study found that more severe forms of scoliosis do not lead to worsening of uneven boobs. 

Hormonal changes

Hormonal changes during puberty, pregnancy, contraception use and menopause can result in small changes to the symmetry of your breasts. Oestrogen and progesterone are the main hormonal drivers of breast tissue growth. This is why you might notice subtle changes to the texture and size of your breast during your menstrual cycle. Breasts are also made up of fat so uneven fat deposits can lead to uneven boobs. 

Breast Cancer

Breast asymmetry is not a sign of breast cancer. One small study demonstrated that uneven boobs could be a risk factor for breast cancer, but this hasn’t been confirmed with large studies. It is important to check your breasts regularly, ideally once a month at the same time of your cycle each time.

Look out for these signs:

• A lump in the breast or armpit
• Changes to your breast skin (irritation or dimpling)
• Inversion (retraction) of the nipple
• Changes to the nipple region (redness or skin flaking)
• Nipple discharge (other than breast milk)
• Swelling of one part of your breast
• Breast pain
• Changes to size and shape of one breast

When to see your GP

The main things to look out for is if the changes in breast asymmetry are new or becoming more pronounced. If you find any changes to your breasts, go to get checked. Your doctor is there to support you and are always happy to see breast changes quickly. 

How to ‘fix’ uneven boobs?

Depending on the degree of unevenness, some cases of breast asymmetry do not need fixing as it’s basically unnoticeable to the naked eye. 

Clothing and bras

Altering your clothing or bras might be an easy fix to uneven boobs. You can try breast inserts to provide some padding to the smaller boob or some camisole bras which evenly distribute the breast tissue a little better. 

Breast asymmetry surgery 

The NHS does not routinely offer breast surgery for cosmetic reasons. There needs to be a noticeable asymmetry to the breast shape, size or nipple position. There are specific criteria you need to meet to have treatment on the NHS depending on your area, and funding may not always be granted. 

Criteria for breast asymmetry surgery may include:

•  a difference of at least 250 grams size
• a BMI of 27 or lower
• a congenital condition causing the breast asymmetry.  

A specialist will be able to assess and determine if surgery is something they can offer you and if it will help.  

We get it, dealing with uneven boobs can be frustrating but also really impactful on your self esteem and mood. Remember it’s common, and if you’re struggling, please speak to someone.