Breast pain after half a month of menstruation may be caused by physiological factors, or it may be caused by breast hyperplasia, breast fibroids and other diseases. 1. Physiological factors: women in the half month after menstruation is in the ovulation period, the body’s hormone levels will change during this time, the secretion of estrogen and progesterone will increase, which will cause breast swelling and pain. After the onset of menstruation, breast swelling and pain will disappear slowly and does not require special treatment. 2. Breast Hyperplasia: caused by menstrual cycle disorders, mental stress, lack of sleep and other factors, the body’s estrogen and progesterone secretion is abnormal, causing breast lobular hyperplasia in the breast, with obvious nodules or lumps, resulting in breast distension and pain, and even nipple overflow. 3. Breast fibroma: Breast fibroma is mainly due to the breast tissue is more sensitive to estrogen, the fibroblasts overgrowth, resulting in hard lumps in the breast, but usually rarely painful, which is related to the individual’s physique and the size of the tumor. At the same time, breast pain also needs to pay attention to whether there are peri-mammary skin diseases, trauma, breast cancer, and non-breast diseases (coronary heart disease, pneumonia) and so on. If the breast pain persists after half a month of menstruation, it is recommended to consult a doctor and standardize the treatment under the doctor’s guidance.