Human chorionic gonadotropin (HCG) is a glycoprotein hormone produced by placental syncytial trophoblast cells during pregnancy and is present in the blood, urine, colostrum, amniotic fluid and fetus of pregnant women and is important for the maintenance of normal pregnancy. In the interaction between the embryo and the endometrium, embryonic-derived human chorionic gonadotropin regulates maternal immune tolerance and promotes embryo implantation. After a woman becomes pregnant, HCG concentrations vary according to a certain pattern, and secretion usually begins 10-14 days after conception. HCG levels in serum and urine can rise rapidly at 1 to 2.5 weeks of gestation, reaching a peak in the 8th week of pregnancy and decreasing to moderate levels by the 4th month of pregnancy, and remaining until the end of pregnancy. The doctor can determine whether the abnormality is a preterm miscarriage, ectopic pregnancy, gravidity, etc. Certain obstetrical and gynecological diseases, post-operative treatment procedures, etc. require tracking changes in HCG blood indicators. HCG injection is often referred to as “human chorionic gonadotropin for injection”, which is commonly used in clinical practice for the prevention of preterm abortion and habitual miscarriage in early pregnancy, and in assisted reproduction for the final maturation of follicles and luteal support in the later stages of the ovulation process. The commonly used dose of intramuscular injection of HCG varies from 1000-10000 IU. Will the HCG test affect the blood HCG value after HCG injection? The answer is yes, the peak time of blood concentration after HCG injection is 12 hours and will reach a stable low concentration after 120h. However, the metabolism level of the drug varies from person to person, and generally speaking, it takes 5-7 days to be completely metabolized in the body, and the test results at this time can basically exclude the interference of the drug. Frequent testing of blood and urine HCG values may cause unnecessary anxiety, and the success of pregnancy depends mostly on the developmental potential of the embryo and the ability of the endometrium to accept the embryo, i.e. endometrial tolerance, after HCG injection with appropriate luteal support. Therefore, it is recommended that we follow the doctor’s advice on medication and keep a good attitude, let’s wait for the arrival of our little angel!