If you have intercourse during the ovulation period, you can detect whether you are pregnant through blood HCG at the earliest 15 days after intercourse, because the fertilized egg can only implant about 15 days after intercourse, and the trophoblast cells will only start to secrete blood HCG after implantation, so the earliest time you can detect whether you are pregnant is 15 days after intercourse through blood HCG. If you want to test by urine HCG, the earliest is 20 days after the coitus, you can do early pregnancy test through morning urine, can detect whether the pregnancy. So clinically, if you want to know whether you are pregnant or not in a hurry, you should take a blood test first. If you are not in a hurry, it is recommended to do the morning and early morning pregnancy test using morning urine 20 days after the intercourse, so that you can know whether you are pregnant or not.