The term “period” is generally used to refer to a woman’s menstrual period. Breast pain can be caused by a variety of reasons, including the onset of menstruation, pregnancy, and other breast diseases. 1. Before menstruation, the hormone level in the body will rise, which may stimulate the breast tissue and produce breast swelling and pain, which is a normal physiological phenomenon. 2. When a woman is pregnant, her hormone levels will rise, prompting breast epithelial cell hyperplasia and ductal dilatation, which may also cause breast swelling and pain. 3. Breast swelling and pain may also be caused by other breast diseases, such as breast hyperplasia, breast nodules, acute mastitis, etc., which may also have symptoms of breast swelling and pain. Breast swelling and pain may also have other causes, it is recommended to go to the regular hospital in a timely manner to improve the relevant examination, under the guidance of a professional doctor to identify the causes, targeted treatment.