Progesterone, also known as luteinizing hormone, is a biologically active natural progesterone secreted by the corpus luteum of the ovary, which plays an important role in the implantation of the fertilized egg and pregnancy, and is necessary for the maintenance of 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 an anti-rejection and inhibits uterine contractions, thus ensuring the smooth and normal development of the fetus in the uterus until full term. The main values range as follows: 0.6-1.9 nmol/L in the follicular phase, 20.7-102.4 nmol/L in the luteal phase, 52.7-100.1 nmol/L in the 7th week of pregnancy, 64.6-113.8 nmol/L in the 8th week of pregnancy, 78-159.2 nmol/L in the 9th-12th weeks of pregnancy, 98.3-185.7 nmol/L in the 13th-16th weeks of pregnancy, and 17-20th weeks of pregnancy. /If the reference unit of the laboratory test is ng/ml, this can be converted to nmol/L units by multiplying by 3.18. If progesterone is too low, it usually indicates luteal insufficiency or premature luteal decline, resulting in poor secretion of the endometrium, which can lead to difficulty in the implantation of the pregnant egg or early miscarriage and inability to maintain the pregnancy. In case of low progesterone, it is recommended to visit a hospital and take natural progesterone supplements for fetal preservation under medical advice, while foods such as soy can be added to assist in increasing progesterone. During the course of progesterone treatment, pregnant women need to follow up regularly and adjust the dosage of medication at any time.