Serum human chorionic gonadotropin is a glycoprotein hormone, consisting mainly of alpha and beta sub-proteins, which is produced mainly by gestational trophoblasts. Patients can produce blood chorionic gonadotropin after pregnancy or in other pathological conditions, such as gestational trophoblastic disease, reproductive tract tumors, and lung, adrenal, and liver tumors. In clinical practice, blood chorionic gonadotropin is most commonly used to monitor a patient’s pregnancy and the development of the gestational sac during pregnancy. Normally, blood chorionic gonadotropin is produced in the trophoblast layer of the fertilized egg on the sixth day after ovulation, and elevated levels of blood chorionic gonadotropin can be detected in the peripheral blood about one day later. It doubles every 1.7-2 days, reaches 100 U/L on the 14th day of ovulation, and peaks at 50,000-100,000 U/L in the 8th-10th week of pregnancy.