Breast enlargement before menstruation is caused by hormonal changes in the body. During ovulation, estrogen reaches its peak and acts on the small ducts of the breast, causing them to develop and thicken within a short period of time. After ovulation, progesterone secretion increases during menstruation, which also affects breast development. It is normal for breasts to become larger and softer before menstruation, but if they persist until after menstruation, it cannot be ruled out that the hormone level is disordered. After the onset of menstruation, progesterone gradually decreases and estrogen levels are at their lowest. If there is also breast enlargement, it cannot be ruled out as breast enlargement or endocrine disorder, etc. If necessary, go to the hospital for breast ultrasound and sex hormone level check, pay attention to a light diet, eat less stimulating food, and do not over-eat food and medicine containing hormones.