There are two kinds of factors that affect the enlargement of female breasts, physiological and pathological, as follows: 1, physiological: related to the level of hormones in the body and pregnancy, the breasts will slowly develop due to the strong secretion of sex hormones in the body of adolescent women, and the increase of estrogen in the body of women after pregnancy will also promote the enlargement of breasts; 2, pathological: related to tumors, when there is a sudden enlargement of breasts, we must pay attention to the situation, there is coitus. If there is no intercourse, it is best to go to the hospital in time for a mammography examination to see if there are breast diseases, and under the guidance of the doctor to actively and effectively carry out treatment. It is best for women to go to the hospital regularly for certain breast examinations, to prevent disease early, to treat disease early, to choose the right underwear, to protect the breast.