The normal value of progesterone for forty days of pregnancy is between 20 and 25 ng/ml. Progesterone is mainly secreted by the ovarian corpus luteum at the beginning of pregnancy and rises gradually with the increase of gestational weeks, and the corpus luteum secretes a sufficient amount of progesterone during early pregnancy which is conducive to the implantation of a fertilized egg and prevents uterine contractions. At 40 days of pregnancy, the normal value of progesterone is between 20 and 25 ng/ml. When luteal insufficiency causes low progesterone, it can increase the risk of early miscarriage. During early pregnancy, as the embryo development is still unstable, it is important to pay attention to not strenuous exercise and exertion, and prohibit coitus. When abdominal pain, vaginal bleeding and other symptoms of pre-eclampsia occur, progesterone and blood HCG (human chorionic gonadotropin) levels should also be measured, and progesterone and other medications should be given to protect the fetus according to the doctor’s instructions, as well as regular ultrasound and progesterone levels should be rechecked.