Causes of Breast Size Change:


Hormonal factors are the single most important cause of changes in a woman’s breast size over a short period of time. It can occur with or during:

  • Menstrual cycle
  • Puberty
  • Pregnancy
  • Use of oral contraceptives or hormone replacement therapy
  • Menopause
  • Gynecological diseases such as poly-cystic ovarian disease (PCOS)

The female hormones causes enlargement of the milk-producing tissue in the breast and may also contribute to breast swelling by the way of temporary fluid accumulation. Hormones can also increase the fat content within the breast over the long term.


Trauma to the breast causes inflammation. This increases the permeability of the blood vessels in the breast and fluid leaks out into the tissue spaces. It may be caused by :

  • Blow to the breast
  • Rough handling
  • Tight brassieres
  • Surgery to the breast

Inflammation is a temporary process and the swelling is accompanied by pain, redness and heat over the skin. It is typically acute and resolves over a short period of time. Anti-inflammatory drugs are often effective in reducing most of the symptoms of inflammation. Usually only one breast is affected.

Breast Disease

Various breast diseases can present with changes in breast size either through inflammation, loss or gain of fat tissue in the breast, the formation of growths and the accumulation of pus. This can affect one or both breasts. These breast diseases include :

  • Fibrocystic breast disease
  • Benign breast tumors
  • Breast cancer
  • Mastitis (breast infection)
  • Breast abscess
  • Breast cyst
  • Galactorrhea

Any change in the breast size or shape has to first be investigated medically before it can be determined whether it is a physiological alteration or due to some pathology (disease). The presence of other symptoms like pain or tenderness, redness, heat, lumps, nipple discharge, changes in nipple appearance and bleeding from the breast are usually indicative of some underlying disease of the breast. However, changes in breast size without other symptoms may not mean it is not due to any disease – it is possible that it is just the first symptom and other symptoms will arise at a later stage. It should be noted though, that the breast size can change with hormonal factors that are in many cases just a normal part of life. Therefore the alteration in breast size may be innocuous and is not a symptoms of any breast disease.