HCG may cause fetal abnormalities as well as abnormal embryonic development and other adverse phenomena. HCG refers to human chorionic gonadotropin, a glycoprotein hormone secreted by placental trophoblast cells, which is mainly used in early pregnancy diagnosis. When the patient’s HCG is low, the possibility of preeclampsia should be considered. When HCG is low or abnormal, it may also lead to fetal growth retardation, abnormal fetal development and arrested development, or cause incomplete development of the trophoblast cells of the embryo, as well as insufficient secretion of human chorionic gonadotropin. Therefore, in case of lower than normal HCG values during pregnancy, patients are advised to take appropriate treatment according to the doctor’s instructions.