Some women’s blood can detect pregnancy eight days after intercourse, but it is not absolute, and some women need to delay two to three days before they can detect it. After intercourse, the sperm and the egg meet and combine to form a fertilized egg. The fertilized egg may implant in the womb in about six to seven days, and after implantation, the trophoblast layer of the fertilized egg is formed, and it starts to secrete a small amount of HCG (human chorionic gonadotropin), so pregnancy may be detected by blood test on the eighth day after intercourse. Some women usually have irregular menstrual cycles, longer menstrual cycles, may have late fertilization after intercourse, the eighth day of intercourse through the blood test can not be temporarily detected pregnancy, should be appropriate to delay two to three days to go back to the blood test for pregnancy. After the same period of time, women should not be too anxious to detect pregnancy, the accuracy of early detection will be lower, the blood test positive, accompanied by the performance of menopause, indicating that the possibility of women’s pregnancy is very high. It is recommended that you go to a regular hospital to take a blood test for pregnancy, so that a professional doctor can determine whether or not you are pregnant.