Normally the significance of progesterone is clearer for women in the third month of pregnancy and can play a role in preserving the fetus, the normal value is around 63.5-95nmol/ml. The reference range will be slightly different in different hospitals and different testing instruments. Progesterone is secreted by the corpus luteum of the ovary during the third month of pregnancy. Since the embryo has just arrived in the uterine cavity and its growth and development is not firm, the increase in progesterone level enables the embryo to be laid, grow and develop normally. If the luteinizing hormone level is low, it can easily lead to lower abdominal pain, vaginal bleeding and other cases of preterm miscarriage. And after the third month of pregnancy, as the secretion of progesterone is also higher, which is supplied by the placenta delivery, the level of progesterone is generally higher, and women pay attention to proper rest and increase nutrition, they are no longer prone to miscarriage.