Pregnancy can be detected before you have your period. Before you have your period, that is, 8-10 days after intercourse, you can go to the hospital to have a blood HCG test. This is because after about 3 days of fertilization and 5 days of implantation after intercourse, the body will secrete blood HCG and the blood HCG test can completely tell if you are pregnant. If you want to know whether you have an intrauterine pregnancy or an ectopic pregnancy, you must have an ultrasound test after more than 40 days to be sure. If you want to know if the embryo is of good quality, you must monitor the doubling of blood HCG, if the doubling of blood hcg value is good, the embryo is of good quality. If the blood hcg value increases slowly or does not increase, or even decreases, it may be necessary to terminate the pregnancy.