If you have sex around the first month of pregnancy and there is bleeding, it is possible that it may lead to a miscarriage. In the early stages of pregnancy, the fetus is not particularly stable. At this stage, if the pregnant woman is engaged in strenuous exercise, or intercourse and poor rest and strain, it may increase the risk of miscarriage. If there is bleeding, you should go to the hospital in time. First, an ultrasound should be done to see if the fetus is developing normally in the womb. Second, blood will be drawn to check for progesterone and chorionic gonadotropin. Patients who do not bleed much may be relieved by rest and taking birth control pills. However, if the bleeding is particularly heavy, the patient will need to be hospitalized to keep the fetus alive and be prepared for the possibility of inevitable miscarriage.