HCG is short for human chorionic gonadotropin, which is secreted by the trophoblast layer of the placenta and allows for the healthy development of the fetus. The value of HCG at 4-5 weeks of pregnancy ranges from 500-10,000 IU/L, but it is only a reference range and there is no fixed value. HCG will change drastically after pregnancy, it can be doubled in the early stage of pregnancy, and will gradually return to a stable value as the pregnancy time increases. HCG level is too low, it will affect the normal conception, and in serious cases, cause miscarriage, so it must be supplemented in time. 4-5 weeks of pregnancy belongs to the early stage of pregnancy, at this time the development of the fetus is still unstable, it is easy to be stimulated by external phenomenon of abortion. Must pay more attention, prohibit strenuous exercise, can not be too tired. In order to ensure the normal development of the fetus should also strengthen the dietary nutrition, eat more protein-rich foods, such as lean meat, fish, soy products and so on.