It is normal for chest swelling to occur before menstruation and disappear after menstruation. Menstruation is regulated by the interaction of reproductive hormones from the hypothalamus, pituitary gland and ovaries. Estrogen and progesterone are relatively low during the menstrual and proliferative phases of the menstrual cycle, and estrogen secretion gradually increases with the development of the follicle. The increase in estrogen in turn stimulates endometrial hyperplasia, and after ovulation the effect of estrogen is switched to progesterone, both of which are felt in the breasts. After ovulation, if there is no pregnancy, estrogen and progesterone will decline, the endometrium will lose the support of these two hormones will appear peeling bleeding, that is to say, menstruation, so the chest distension before menstruation, after menstruation because of the decline in the level of hormones and chest distension disappeared, which is very normal.