The accuracy of pregnancy blood test is relatively high. When a woman is pregnant, the gestational trophoblast cells will secrete HCG hormone, and the human chorionic gonadotropin in the body will rise, so you can determine whether you are pregnant by drawing blood to check the human chorionic gonadotropin in your blood. After ovulation, sperm and egg combine to form a fertilized egg, the human chorionic gonadotropin in the body will rise significantly, about a week or so after intercourse, you can draw blood to check the blood HCG to determine whether you are pregnant or wait until the regular menstruation is delayed to draw blood for examination, such as the value of the examination exceeds the normal value, which means that it is pregnant. It should be noted that trophoblastic diseases such as hyperemesis gravidarum or ectopic pregnancy may also have elevated blood HCG, therefore, to determine intrauterine pregnancy, in addition to blood HCG should be combined with ultrasound comprehensive judgment.