It takes about 15 days after intercourse to test if you are pregnant. This is mainly because it takes 1.5-6 hours after the sperm is ejaculated into the vagina before it reaches the fallopian tube and unites with the egg. After uniting with the egg, a fertilized egg is formed. The fertilized egg then peristalsis of the fallopian tube takes an average of 9-13 days to enter the uterine cavity. After entering the uterine cavity, the fertilized egg does not settle immediately, but spends 2-3 days in the uterine cavity. The purpose of its freeing is to find a suitable location for implantation. After implantation, the trophoblast cells can secrete blood HCG, which means that it is only after implantation that pregnancy can be detected by blood HCG, or urine HCG. Therefore, it takes about 15 days from the day of intercourse until the pregnancy can be detected.