The normal value of progesterone in the third week of pregnancy is usually around 25ng/mL. Progesterone can reduce the excitability of uterine muscles, inhibit contractions, inhibit the immune response, and maintain the ecchymotic response, and thus is an important hormone for maintaining pregnancy. It is secreted partly by the placenta of the fetus and partly by the ovaries of the mother, and changes dynamically as the weeks of pregnancy increase. If the result is lower than 15ng/mL, it is necessary to strengthen the monitoring of progesterone and human chorionic gonadotropin, on this basis, accompanied by vaginal bleeding, abdominal pain and other symptoms, it is necessary to be vigilant about whether there is an ectopic pregnancy or the occurrence of miscarriage, and if necessary, can be used as appropriate to supplement the natural progesterone to achieve the purpose of preservation of the fetus. If the HCG doubles normally and the progesterone level is greater than 25ng/mL, the possibility of ectopic pregnancy can be basically ruled out, and then determined to be intrauterine pregnancy.