Suddenly before the menstrual period, the breasts do not bloat pain, consider may be early pregnancy, drug factors, ovarian function decline and other causes. 1. Early pregnancy: women before menstruation, because the body’s estrogen level is relatively high, often lead to breast swelling and pain, but if the body’s hormone level will change after pregnancy, may lead to breast swelling. 2. Drugs: Often caused by taking progesterone drugs, for example, taking dydrogesterone tablets or progesterone capsules in the second half of the menstrual cycle will lead to an increase in progesterone, and the symptoms of breast swelling and pain have been relieved. 3. Decline in ovarian function: After women enter perimenopause or experience premature ovarian failure, estrogen levels will decrease, and there will be no obvious breast pain before menstruation. Suddenly before menstruation, breast pain, there may be other reasons, if accompanied by other symptoms of discomfort, it is best to go to the hospital, to clarify the cause of targeted treatment or treatment.