For women with accurate menstrual cycles, a pregnancy test can usually be used 15 days after intercourse to detect pregnancy more accurately. After intercourse during ovulation, it takes 24 hours for the sperm and egg to unite and form a fertilized egg. As the fertilized egg lays and develops in the uterus, the human chorionic gonadotropin is secreted in the woman’s body during the process of placenta formation, and generally HCG can be detected in the blood about a week after intercourse, but it takes some time to be detected in the urine, usually about 1-2 weeks. Therefore, a woman can use a pregnancy test to detect HCG more accurately about 15-20 days after intercourse. If the pregnancy test does not detect the pregnancy, the diagnosis can be confirmed by taking a blood test for HCG. In addition, for women with delayed menstruation, it can be detected usually 6 weeks after menopause. If the result of the pregnancy test is not obvious or not easy to determine, it is also recommended to take a blood test for HCG at the hospital and the result of the blood test will prevail.