Breast swelling causes more, according to the different diseases that lead to breast swelling, the causes are mainly divided into the following situations: First, the normal growth and development of the mammary glands during puberty, both men and women may have a certain degree of breast swelling or pain, is a normal phenomenon does not need treatment. Secondly, breastfeeding women, due to normal lactation needs or even milk stagnation, the breast will have a certain degree of swelling, need to do a good job of breast care, to prevent acute mastitis. Third, before menstruation, the body estrogen level rises to stimulate breast swelling, usually after the end of menstruation, estrogen levels return to normal, swelling will be restored. Fourthly, mild breast hyperplasia may cause swelling in the breast area because of the abnormally high estrogen level in the body. Fifth, benign tumors and cysts in the breast, such as breast fibroma and breast cysts, due to the enlargement of the swelling of the breast will be distended. Sixth, malignant breast tumors, malignant tumors have no obvious pain in the early stage, but there can be discomfort in the breast area, and some of them show swelling.