Breast pain is mainly considered for the following reasons: 1, menstruation: non-menopausal women after menarche, the body hormone level will change with each monthly menstrual cycle, before and during menstruation, the body estrogen level is rising, at this time the breast will be enlarged, so produce swelling and pain sensation; 2, mastitis: breastfeeding women do not suckle or breastfeeding in time, resulting in a large amount of milk stagnation in the mammary gland, or not timely cleaning of the nipple surface of the milk breeding bacteria, resulting in bacterial upward infection and mastitis; 3, breast tumors, lumps: accompanied by uneven skin surface, with secretions or subcutaneous lumps can be palpable.