Before menstruation, the breasts become bigger because of the hormonal changes in the body, women in the ovulation period estrogen will reach its peak, acting on the mammary ducts, a short period of time to make its development, thickening, there will be a bigger breast. After ovulation, progesterone begins to increase during menstruation, and also acts on breast development. It is normal for breasts to become bigger and softer before menstruation, and if it continues to exist after menstruation, it cannot be ruled out that the hormone level is disturbed. After menstruation, progesterone gradually decreases and estrogen levels are at their lowest. If there is still breast enlargement, it can not be ruled out that it is breast hyperplasia, endocrine disorders, etc. If necessary, go to the hospital to do breast ultrasonography and sex hormone levels, usually pay attention to light diet, eat less stimulating food, do not over eat food and drugs containing hormones.