Depending on the test method, there are some differences in how long it takes to detect pregnancy after intercourse, and each case needs to be analyzed on a case-by-case basis. In general, pregnancy can be detected by blood HCG about 10 days after intercourse during ovulation. In daily life, pregnancy can also be detected by the simpler and more common early pregnancy test paper, but it can only be detected after 2 weeks of coitus, and it is recommended to use mid-morning urine, and this method can only be used as a reference for self-testing, and there is a certain degree of false-negativity. In addition, uterine ultrasound can also be used to determine whether the pregnancy, but the time is relatively later, about 3 weeks after intercourse, that is, the menstrual period is delayed for 1 week before you can observe whether there is a pregnancy sac in the uterine cavity. It should be noted that the early blood HCG index can only detect whether the pregnancy, as to whether it is a normal intrauterine pregnancy, you need to go to the gynecologist to confirm whether the gestational sac is in the uterine cavity through ultrasound monitoring.