Blood can detect pregnancy. When the sperm and egg combine to form a fertilized egg, the fertilized egg can run into the uterine cavity and settle in the uterus. As the fertilized egg continues to differentiate and develop, it can differentiate into syncytiotrophoblast cells, and the syncytiotrophoblast cells will secrete the unique human chorionic gonadotropin, which can enter into the blood of the mother, and pregnancy can be detected through the monitoring of human chorionic gonadotropin levels in the mother’s blood. In addition to detecting pregnancy, human chorionic gonadotropin levels can also assist in the diagnosis of ectopic pregnancy, hyperemesis gravidarum and other diseases. In the case of ectopic pregnancy, human chorionic gonadotropin levels are usually relatively low and multiply over a long period of time; in the case of hyperemesis gravidarum, human chorionic gonadotropin levels are usually too high, and are sometimes even dozens of times higher than the normal value. If the patient confirms the pregnancy, should be under the guidance of a professional physician in time to avoid the delay of the disease, resulting in adverse consequences.