It is not possible to check for 3 days of pregnancy. There are two ways to check for early pregnancy: blood HCG and early pregnancy test paper. Blood HCG is the earliest and needs to be checked 8-10 days after intercourse. Normal non-pregnant women’s blood and urine can not be detected HCG; sperm and egg combination from the fallopian tube to the uterine cavity to run for about 3 days, to the uterine cavity, the fertilized egg splits and develops to a certain stage with the conditions of the bed, before planting to the uterine lining, and the mother to establish a blood circulation, this time about 8-10 days after the fertilization, can only be detected from the mother’s blood to the fetal chorionic villus secretion of human chorionic gonadotrophin (HCG), and the maternal blood circulation is established. Human chorionic gonadotropin (HCG) can be detected in the mother’s blood about 8-10 days after fertilization, and rises gradually with the number of days of pregnancy, or in the urine, which is the most accurate and earliest to be detected by drawing blood from a vein. Early pregnancy tests require a certain concentration of HCG in the urine to be detected, which is subject to time constraints and the method of operation, and is subject to a certain degree of error. Women who do pregnancy self-tests at home do so without professional guidance, and the test results are generally only 75% accurate. If the test is conducted under the guidance of a doctor, it can ensure the correct use of early pregnancy test paper, and the accuracy of the test will be higher. Understanding the principle of early pregnancy test, a short period of time after coitus wondering whether they are pregnant, it is not recommended to rush to the hospital to do the test, patiently wait, at least 10 days later to the hospital to do the test. Early checkups increase the number of checkups and costs for no reason, and the error is also greater. However, if vaginal bleeding occurs, you should consult a doctor promptly to rule out ectopic pregnancy or hyperemesis gravidarum.