Hormone changes during the menstrual cycle likely lead to breast swelling. More estrogen is made early in the cycle and it peaks just before mid-cycle. This causes the breast ducts to grow in size. The progesterone level peaks near the 21st day (in a 28-day cycle). This causes growth of the breast lobules (milk glands).

Premenstrual breast swelling is often linked with:

Premenstrual breast tenderness and swelling probably occur to some degree in nearly all women. More severe symptoms may occur in many women during their childbearing years. Symptoms may be less in women taking birth control pills.

Risk factors may include: