Women taking progesterone have thickening endometrium, which generally refers to the thickening of endometrium during progesterone taking, mainly caused by the effect of the drug. Because progesterone is a progestin drug, women will take it to thicken the endometrium, which will gradually fall off after stopping the drug. Because progesterone is a progestin and has the function of protecting the endometrium, it is normal for women to experience thickening of the endometrium while taking progesterone. Progesterone can also inhibit the contraction of the smooth muscle of the uterus, so it has a clinical effect on the fetus. After progesterone is taken orally in a non-pregnant state, it can thicken the endometrium. When the drug is discontinued, the endometrium will shed and cause vaginal bleeding due to the loss of exogenous progesterone support, which can be used to treat conditions such as menstrual disorders caused by progesterone deficiency. In addition, if you are already pregnant, the sperm and egg combine to form a fertilized egg, and the fertilized egg gradually enters the uterine cavity and lays, the gestational sac cannot be seen through ultrasound, but the endometrium becomes thicker and thicker, the blood HCG shows positive results, and ultrasound examination is done again in about 1 week, and the gestational sac can usually be seen, so taking progesterone causes the endometrium to become thicker and thicker, and if there is no vaginal bleeding for about 8 days after stopping the medication, pregnancy should be ruled out as possibility. In daily life, it is recommended that women have regular medical checkups to understand the recent physical condition, and if abnormalities appear, try to achieve early detection and early treatment. In addition, if a woman is unwell after taking progesterone, it is recommended to consult a doctor promptly and decide whether to stop the medication or switch to other medication after the doctor’s examination to clarify the cause.