If a woman who normally has regular menstrual periods has sex, and her period comes on time that month, she is not pregnant. If the hormone levels in the body change during pregnancy, the most typical symptom is menopause, which is one of the earliest clinical manifestations of pregnancy, as long as you are sure that you are having a normal period, it means that you are not pregnant. However, it is important to make sure that it is menstruation, because some women in the early stages of pregnancy may also experience a small amount of vaginal bleeding for various reasons, such as miscarriage with precursor, fertilized egg implantation, ectopic pregnancy and so on, because it is easy to be confused with menstruation, some patients directly think that it is menstrual disorders, and thus do not pay attention to it. Therefore, we must look at the amount of menstruation and the time of menstruation to see if it is consistent with the usual menstruation. If the amount is significantly reduced or the time is significantly abnormal, it is still necessary to go to the hospital for a pregnancy test.