The causes of breast swelling and pain are as follows: First, adolescent breast swelling and pain, the first type is that women generally occur at the age of 9-13, and the swelling and pain will disappear on its own after the first period. Second, premenstrual breast pain, mainly because of the premenstrual body estrogen levels increase, caused by inter-breast tissue, such breast pain will gradually disappear after the menstrual period. Third, breast pain during pregnancy, pregnancy because the placental villi secrete a lot of estrogen, progesterone, prolactin, resulting in breast enlargement, resulting in breast pain, this breast pain is also a normal phenomenon, without treatment. Fourth, postpartum breast pain, postpartum breast pain is due to lymphatic retention in the breast, venous filling and interstitial edema, as well as poor ducts of the breast. Fifth, breast swelling and pain after abortion, if suddenly interrupted during pregnancy, will also cause breast swelling and pain, because the body’s hormone levels suddenly drop, so that the newly developed breast suddenly stop growing, resulting in breast and breast pain. Sixth, breast pain after sex, some women will also occur after sex breast pain, this is mainly related to the physiological changes in the breast during sex.