The normal reference range for human chorionic gonadotropin is 10,000-100,000 mIU/mL at 40 days of pregnancy , and as the pregnancy grows, so does the chorionic gonadotropin, which can double approximately every day. Human chorionic gonadotropin, a protective hormone secreted by trophoblast cells, protects against attacks by the maternal immune system. It is possible to determine intermittently whether the fetus is developing normally from the value of the human chorionic gonadotropin, but it is also necessary to combine it with the value of progesterone. If the value of human chorionic gonadotropin is significantly low in early pregnancy, you should be alert to the possibility of poor fetal development or ectopic pregnancy, which can be more accurately understood by ultrasound examination after 42 days of pregnancy.