Pregnancy can usually be detected half a month after intercourse. Some patients can detect it by using early pregnancy test paper, and the result will be more accurate if they go to the hospital to draw blood for HCG. Generally, after 6-7 days of intercourse, the embryo implants in the endometrium and starts to secrete HCG gradually, which can be detected in the serum in about half a month. At this time, if the woman’s urine is tested with early pregnancy test paper or blood is drawn for HCG, and if it is positive, pregnancy can be diagnosed. Compared with the blood test, the result of the blood test is more accurate because HCG is produced by the fertilized egg after it is laid in the blood first, and a small amount enters the urine thereafter, so the urine HCG can be detected about 3 days later than the blood HCG. However, it should be noted that either the early pregnancy test or the blood HCG test can only diagnose whether a pregnancy is present, but to determine whether it is intrauterine, further examination by ultrasound is needed. Once pregnancy is confirmed, pregnant women should avoid various risk factors that affect embryonic differentiation and fetal development, such as radiation, smoking and alcohol, stay away from various toxic substances, such as benzene, lead, mercury and arsenic, and avoid viral infections, especially rubella virus infection.