Serum human chorionic gonadotropin (HCG) is a hormone secreted by the embryo after its implantation, which can be secreted 7 days after the sperm-egg union and can be measured in the mother’s blood in 10 days, and as long as the human chorionic gonadotropin is detected in the blood at a level higher than the normal value, the diagnosis of pregnancy can be confirmed. Therefore, in clinical practice, we determine pregnancy based on the presence or absence of serum human chorionic gonadotropin in the early stages of pregnancy, and we can also detect changes in serum human chorionic gonadotropin to understand whether the development of the embryo is normal or not. A low level of serum human chorionic gonadotropin changes in early pregnancy may indicate poor embryonic development or cessation of embryonic development. Typically, in the early stages of pregnancy the embryonic tissues just secrete serum human chorionic gonadotropin at a low level, and as the pregnancy progresses, its value increases rapidly, and typically there is an exponential increase in serum human chorionic gonadotropin every 24 to 48 hours. Therefore, in the early stages of pregnancy, if the serum human chorionic gonadotropin value is found to be low, the patient is advised not to be overly nervous, and only need to re-check the serum human chorionic gonadotropin every other day to observe whether its growth rate is normal or not, so as to infer whether or not the development of the embryo is normal or not. At present, the clinical concern is not the specific value of serum human chorionic gonadotropin, but to determine the embryonic development by observing the growth rate of serum human chorionic gonadotropin. Therefore, in the early stages of pregnancy when serum human chorionic gonadotropin levels are low, it is necessary to observe its growth rate to determine embryonic development.