It is inaccurate to say that breast tenderness before menstruation proves that the patient is not pregnant. Breast tenderness is caused by the increase in estrogen and progesterone levels before menstruation, which leads to the physiological growth of the mammary glands. After pregnancy, estrogen and progesterone will rise sharply, so it will stimulate the physiological growth of the mammary ducts, mainly to prepare for breastfeeding after delivery. So this sentence is interpreted the other way around, it should be said that breast swelling and pain before menstruation is more likely to be pregnant. However, there is no necessary relationship between breast tenderness and pregnancy. If the patient has delayed menstruation, it is necessary to rely on the blood or urine chorionic gonadotropin to determine whether or not conception has occurred, and there is no way to determine this by simply observing the breast tenderness.