Reasons for Breast Swelling

The breasts undergo cycles of growth and development in response to circulating hormones. Tissues within the breast are designed to facilitate milk production and lactation during and after pregnancy, and help support and shape the structure of the breast. Breast swelling may develop because of underlying conditions or potentially harmful disorders.


Breast swelling naturally occurs during pregnancy in response to high levels of female hormones. During pregnancy, estrogen and progesterone levels increase dramatically and signal to a number of tissues throughout the body to prepare the woman’s body to support a child. Cells within breast tissue respond to estrogen by proliferating, leading to an enlargement of the internal structure within the breast. This rapid growth leads to breast swelling and may cause tenderness and a change in breast consistency, reports the Ohio State University Medical Center. Breast swelling as a result of pregnancy will continue until the mother stops breastfeeding.


Another cause of breast swelling is lymph obstruction. The breasts are surrounded by a number of lymph nodes, structures that help make up the lymphatic and immune system. The lymph nodes are connected by a series of vessels, and the nodes are involved in the circulation of lymphatic fluid. If lymph circulation is obstructed, lymph fluid can accumulate around the blockage, a condition called lymphedema. If the block occurs near the breast tissue, lymph fluid accumulation can lead to breast swelling. The swelling can be painful and require medical attention. Dr. Nicole Gergich, writing for, notes that compression bras can be used to treat lymphedema in the breast.

Inflammatory Breast Cancer

A potentially fatal cause of breast swelling is inflammatory breast cancer. IBC is a rare form of cancer that accounts for approximately 5 percent of breast cancer cases in the United States, according to the National Cancer Institute. Patients with IBC experience swelling, redness and warmth of the breast, which may be accompanied by skin abnormalities such as dimpling and wrinkling.

IBC can be diagnosed following imaging analysis of the breast, and treated with an aggressive strategy that may include surgery, chemotherapy, radiotherapy and targeted therapies. IBC is very aggressive, with an average five-year survival rate between 25 and 50 percent, reports the National Cancer Institute.

About this Author

Louise Tremblay recently finished an M.Sc. in molecular and cellular biology in Ontario, Canada, with years of cancer research experience. She has experience writing articles and Web content on science, heath and fitness, diet and personal wellness.