There is a clear difference between redness during pregnancy and menstruation. In terms of timing, pregnancy has a history of menopause, while menstrual bleeding has no history of menopause and menstruation follows a regular pattern. In terms of the amount of bleeding, redness of pregnancy bleeding is less. In terms of the nature of the bleeding, pregnancy bleeding blood is clotted, while bleeding during menstruation is a non-clotted blood. In addition, there are pregnancy reactions such as nausea, vomiting, breast swelling, and symptoms of early pregnancy reaction during pregnancy, while there are no such symptoms during menstruation, and sometimes there can be slight breast swelling and slight lower abdominal discomfort. The diagnosis can be clarified by auxiliary examinations. Ultrasound examination after pregnancy can reveal hyperechoic areas in the uterine cavity with pregnancy products, while there are no abnormal echoes in the uterus during menstruation, and urine tests can show positive urine pregnancy, or increased levels of progesterone and HCG in the blood, which are within the normal range during menstruation.