HCG is a human chorionic gonadotropin that contains both alpha and beta subunits. alpha-HCG has a fixed 3:1 ratio to beta-HCG, and even though HCG and beta-HCG units are the same, HCG is four times larger in value than beta-HCG after conversion, making HCG larger than beta-HCG. beta subunit is specific to HCG. It is the specific antigen in the immunological pregnancy test, i.e. the beta subunit is measured when measuring whether a woman is pregnant or not. In clinical practice, pregnancy can be considered if HCG and beta-HCG are found to be significantly elevated. At this point, a woman can go to the hospital to have their numerical levels tested. HCG test values are calculated from the formation of the fertilized egg, while beta-HCG tests are calculated from the last menstrual period, i.e. the gestational week of pregnancy. In addition, when HCG or beta-HCG is increased, it can also be certain tumors, such as some gynecological tumors and gastrointestinal tract tumors, which are able to secrete HCG in larger amounts, similar to the level of early pregnancy, and can have no specific clinical manifestations. Usually, one of the HCG and β-HCG tests is sufficient, even if the values are different, the clinical significance is the same, so it is not necessary to test both.