Breast pain and swelling eight days before menstruation is mostly not a sign of early pregnancy, but a normal physiological phenomenon. The period before menstruation is the luteal phase of the menstrual cycle. After ovulation, the ovary forms the corpus luteum, which secretes estrogen and progesterone to maintain the uterine lining. Estrogen stimulates the growth of ductal cells and alveolar cells in the mammary glands, and increases the permeability of local blood vessels, leading to breast enlargement and sometimes pain. This is generally a normal physiological phenomenon and usually returns to normal after menstruation. However, it is also necessary to rule out the possibility of mammary hyperplasia, breast nodules, or even breast tumors.