After intercourse, the fertilized egg is still inside the fallopian tube, and it takes about 1 week of peristaltic movement through the fallopian tube to reach the uterine cavity, and only after it has settled in the uterine cavity, the trophoblast layer of the embryo secretes human chorionic gonadotropin to reach the woman’s bloodstream. Therefore, it can only be detected in the blood until about 7 days after intercourse at the earliest. The pregnancy test is a test of urine, if it is dark and light, it means that a little hormone level has been shown in the urine, and most of this situation is seen 10 days after intercourse.