There are two most common reasons for women to experience breast pain a few days before menstruation: 1, physiological changes: for physiological changes, mainly women’s hormone levels in the body before menstruation will change significantly, especially changes in the body’s lactogen, which will lead to some changes in the mammary glands, thus resulting in distension and pain. 2, breast hyperplasia or other mammary gland diseases: if there is a more obvious pain before each menstrual period If the pain is more pronounced before each period, consider the presence of breast hyperplasia, which requires a breast examination by ultrasound. Breast enlargement is strictly a physiological change, the main reason is that after the completion of female breast development, the body’s estrogen level is abnormally high, resulting in the secondary development of the breast, usually through the use of hormone drugs to regulate. Premenstrual breast pain may also occur in some obvious breast diseases, including breast cysts, breast fibroadenomas, etc., which can be detected by ultrasound.