Clinically, progesterone is mainly secreted by the ovarian corpus luteum and to a lesser extent by the adrenal glands during the non-pregnant phase and can contribute to the transformation of the endometrium from the proliferative phase to the secretory phase. The normal values and significance of progesterone in normal pregnant women of reproductive age vary when blood is drawn for testing at different periods of the menstrual cycle, mainly including early follicular phase, late follicular phase, early luteal phase, and late luteal phase. The progesterone value of 0.2 in women who are not pregnant, generally refers to 0.2μg/L, may belong to the low value of progesterone.1. early follicular phase: the endometrium in the early follicular phase is in the value-added phase, progesterone is also at a low level, the normal value is generally 0.7±0.1μg/L. The progesterone value of 0.2ng/ml in women who are not pregnant at this time is normal; 2. late follicular phase: this is close to ovulation, the endometrium is gradually changing from the proliferative phase to the secretory phase, progesterone is not normal. The normal value of progesterone is 0.4±0.1μg/L. If progesterone 0.2 in women of childbearing age who are not pregnant at this time is abnormal; 3. Early luteal phase: for women with a menstrual cycle of about 28 days, the normal value of progesterone should be 11.6±1.5μg/L on the 21st day of menstruation, suggesting ovulation. If the progesterone value is <3ng/ml, it indicates no ovulation. Therefore, a blood test showing no pregnancy with a progesterone of 0.2ng/ml is abnormal; 4. Late luteal phase: At this time, the progesterone concentration reaches its peak and the normal value of progesterone is 5.7±1.1μg/L, suggesting normal ovarian function. If the blood test for progesterone at this time shows 0.2ng/ml, it is an abnormal condition, suggesting abnormal ovarian function. Progesterone has a role in determining ovulation and diagnosing luteal insufficiency in the non-pregnant period, and in the pregnant period, it has a role in determining the prognosis of in vitro fertilized embryo transfer, and identifying ectopic pregnancy. The normal range of values varies depending on the timing of the test. It is important to choose the testing time by clarifying the testing purpose in order to correctly assess the normal values and clinical significance of different hormones, and also to better guide clinical problem solving.