Twelve days after intercourse, pregnancy can usually be detected with a pregnancy test. Pregnancy tests help diagnose early pregnancy by measuring the presence of human chorionic gonadotropin (HCG) in the urine of a pregnant woman. HCG is produced in a pregnant woman’s body when a fertilized egg implants in the uterus. HCG is a glycoprotein hormone secreted by the trophoblast cells of the placenta, and the production of HCG, a hormone that normally begins after the fertilized egg has been deposited and rises rapidly 14 days after ovulation. For women who have stopped menstruating it can be detected in the urine about 12 days after intercourse. In women who have regular periods, pregnancy can usually be detected around 35 days after menopause by a urine pregnancy test and a blood test for HCG. Around 40 days after menopause you can also use gynecological ultrasound to detect whether the location of the pregnancy sac is in the uterus. Therefore, 12 days after intercourse, you can use the test paper to find out whether you are pregnant or not, but sometimes when the HCG is relatively low, there will be false negatives, and it is recommended to go to the hospital to take blood to check HCG to determine whether you are pregnant or not.