Uneven or Mismatched Breasts: Causes, Treatments, Risks & More

  • Uneven breasts occur when one breast differs from the other in size, shape, position or volume
  • Some variation between breasts is very common and not cause for concern 
  • Breasts that differ significantly or suddenly change in density could be indicative of breast cancer 
  • Treatment options include breast augmentation surgery, prostheses and breast reduction
  • Ideals candidates should be in good health with no underlying health conditions

When a woman’s breasts differ in size, volume or position, they are referred to as uneven or asymmetrical. Most women do have slight differences, and this is entirely normal.

When there’s a greater variation between breasts, this can have an affect on self-esteem. Fortunately, there are corrective surgeries available to achieve a more balanced appearance, with breast augmentation and reduction being the most common solutions. 

What Defines Uneven Breasts?

Uneven breasts occur when one breast is different in size or shape from the other.

How Do Uneven Breasts Occur?

There are several causes as to why a woman’s breasts can change in size or volume. These include:

  • Aging
  • Breast infection
  • Breastfeeding
  • Hormonal fluctuations
  • Pregnancy
  • Puberty
  • Trauma
  • Weight gain or loss

Uneven breasts are a natural occurrence and fluctuations in breast size and shape can commonly occur over time. However, when the difference in appearance is sudden or dramatic, this could be a sign of an underlying health condition, such as the following.

Atypical ductal hyperplasia

Atypical ductal hyperplasia (ADH) is a precancerous condition where abnormal cells accumulate in the breast duct. This can cause the breast to be irregular in both shape and size.  

Breast cancer

Studies have shown a correlation between uneven breasts and cancer; in addition, it is understood that the greater the asymmetry, the higher the risk. In one study, researchers found   breast asymmetry was greater in women who later developed breast cancer than in women who remained disease-free.

Hypoplastic breasts

Hypoplastic breasts are undeveloped breasts with insufficient glandular tissue. Breast hypoplasia can occur in one breast or both; if the latter, breasts can be symmetrical or asymmetrical. 

Juvenile hypertrophy

Breasts can be asymmetric due to juvenile hypertrophy which is a benign condition that occurs during puberty and is characterized by an alarming, rapid and continuous breast growth. Uneven breast development can affect one breast or both. 


Pregnancy triggers fluctuations in hormone levels which causes breasts to increase in size and shape. Post pregnancy breasts will likely remain altered and one breast may be uneven. 

What Are the Benefits of Corrective Measures?

For most women, a slight difference between breasts is barely noticeable. For others who have a significant difference in breast size, volume or shape, corrective treatments can effectively improve their silhouette and restore confidence.


The following are three established corrective solutions to help women achieve a symmetrical balance:

Breast augmentation

Breast augmentation involves inserting an implant into the smaller breast to increase the size and fullness for a balanced appearance. Overall, breast augmentation is most effective for minimal to moderate asymmetry. 

Breast prosthesis

If surgery is not an option, a breast prosthesis is a noninvasive solution that can provide you with a more uniform appearance. A breast prosthesis is a silicone, foam or fiberfill shell that fits over the smaller breast so that both breasts appear similar. A prosthesis would be best for women experiencing significant breast asymmetry.

Breast reduction

Breast reduction surgery is a procedure that removes excess fat, tissue and skin from the larger breast. During the procedure, issues such as imbalances in size, shape and nipple position can be corrected.

Ideal Candidates

Ideal candidates for corrective surgeries are in good health with no underlying health conditions and reasonable expectations. Corrective surgery is not recommended if you are pregnant or breastfeeding, have breast cancer or an abnormal mammogram.


As with any surgery, there are certain risks involved with correcting uneven breasts, as follows. 

Breast augmentation

  • Anesthesia complications
  • Changes in nipple or breast sensation
  • Fluid accumulation 
  • Capsular contracture (scar tissue surrounding an implant)
  • Implant leakage or rupture 
  • Infection 
  • Persistent pain 
  • Wrinkling of skin over breast implants

Breast reduction 

  • Anesthesia complications
  • Blood clots
  • Changes in nipple or breast sensation
  • Damage to deeper structures such as nerves, blood vessels, muscles and lungs
  • Fat necrosis
  • Fluid accumulation
  • Hematoma (bleeding)
  • Infection
  • Potential loss of skin/tissue of breast where incisions meet each other
  • Potential, partial or total loss of nipple and areola
  • Skin discoloration


Having uneven breasts is a very common occurrence among women. Breasts can fluctuate in size, shape and volume at various life stages including puberty, pregnancy and birth, and with weight gain and loss. 

Many women have only a slight asymmetry and are comfortable with their appearance. For others, a significant difference in breast size and volume can have a negative impact on self-image and confidence. Corrective solutions such as breast augmentation, reduction and prostheses can provide balance, improve the appearance and restore confidence.

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