Women with symptoms of breast pain before menstruation are not necessarily pregnant, the reasons are mainly these: 1, endocrine disorders, before menstruation if emotional anxiety, tension, and irregular life, estrogen and progesterone secretion is unbalanced, too much estrogen, too little progesterone, will lead to significant changes in the body, breast pain is one of the symptoms. 2, pregnancy, breast swelling and pain before menstruation, it is possible that Pregnancy, a large amount of estrogen secretion after pregnancy, will cause the breast ducts to gradually expand. The breast pain can be determined by checking the human chorionic gonadotropin. 3, breast nodules, if there are nodules or mastitis, poor blood circulation around the breast will also lead to breast pain, the symptoms will be more obvious before the period, need to be diagnosed in time.