It can be detected about 10 days after fertilization. After successful fertilization, the syncytial trophoblast cells secrete human chorionic gonadotropin, which is found in the blood and urine, and the amount is small at the beginning of fertilization and cannot be easily detected. Pregnancy can be determined when the chorionic gonadotropin contained in the blood is elevated above the normal range. You can also test with a pregnancy test 7 days after your period is delayed, and the presence of two bars on the test means that conception has occurred. In the early stages of pregnancy, to determine the healthy development of the embryo, the level of human chorionic gonadotropin can be tested every other day. The presence of doubling every other day indicates a well-developed embryo, and a pelvic ultrasound should be done at 5-6 weeks of menopause to exclude ectopic pregnancy. In early pregnancy, the placenta has not yet formed and the embryo is still unstable and easily stimulated by the outside world. You should pay more attention to rest, avoid straining and take more nutrition to ensure the healthy development of the fetus.