The normal value of progesterone at 40 days of pregnancy is not standardized now, and can be checked by regular blood draws. Generally, the follicular phase in women is 0.6-1.0 nmol/L, during ovulation 1.0-11.2 nmol/L and after ovulation 20.8-103.0 nmol/L. Progesterone is a biologically active natural progesterone secreted by the corpus luteum of the ovary and plays an important role in the fertilization of the egg and pregnancy. A sufficient amount of progesterone not only ensures the normal function of the endometrium and promotes the normal development of the embryo, but also has anti-rejection and inhibits uterine contractions, thus ensuring the smooth and normal development of the fetus in the uterus until full term. If progesterone is too low, it usually indicates luteal insufficiency or premature decline of the corpus luteum, resulting in poor secretion of the endometrium, which leads to difficulty in the implantation of the pregnant egg or early miscarriage and inability to maintain the pregnancy. It is recommended to go to the hospital and need to use progesterone and other medications under the guidance of the doctor for fetal preservation. At the same time, pregnant women should pay attention to rest and strengthen diet and nutrition, and it is recommended to eat more vegetables and fruits. If there is an aura of miscarriage, it is best to rest in bed. At the same time, it is recommended to take reasonable vitamin E supplements, which can prevent miscarriage, and it is best to have regular ultrasound examinations to observe the development of the baby, as long as the baby develops normally, the effect is not significant.