The unit of HCG is IU/L (international unit/liter) or mIU/ml (millinternational unit/ml), although the name of the unit is different, but in fact the size of the value remains the same and the value of HCG concentration in blood or urine is the same, i.e. 1mIU/ml = 1IU/L. HCG is also called human chorionic gonadotropin, which is a glycoprotein unique to women during pregnancy secreted by the trophoblast of the placenta. HCG, also known as human chorionic gonadotropin, is a glycoprotein secreted by the placental trophoblast after pregnancy. HCG can be detected in the peripheral blood 7 days after fertilization, and rises rapidly from 6 to 8 weeks of pregnancy, increasing 1-fold every 2-3 days and reaching a peak from 8 to 10 weeks of pregnancy. HCG test is currently a more accurate method to diagnose early pregnancy, and the dynamic changes of HCG are of great value in diagnosing and identifying pathological pregnancy, and can reflect to some extent the development of the fetus in the mother. If HCG rises slowly or decreases in early pregnancy, it suggests a possible ectopic pregnancy, embryonic abortion, spontaneous miscarriage, or pre-eclampsia. If HCG is abnormally elevated, it may be a trophoblastic disease such as chylothorax or choriocarcinoma. In addition, HCG is also useful in the diagnosis and monitoring of other tumors, such as breast cancer, testicular cancer, ovarian cancer, etc. HCG stimulates the body to produce progesterone, which can work synergistically with progesterone to protect and nourish the embryo and is important for fetal preservation and maintenance of pregnancy.