If vaginal bleeding occurs while taking progesterone, it is often caused by the following factors: 1. the dose of progesterone taken is not enough to maintain the dose of progesterone needed in the body, the endometrium will shed and bleeding will occur. it is recommended to increase the dose of progesterone taken to improve the situation of bleeding while taking the drug. 2. because the progesterone in the body has a tendency to decline. The endometrium is already shedding after the progesterone in the body has dropped, and taking progesterone again is not enough to repair the endometrium, so the bleeding will occur. It is recommended that this situation immediately stop taking progesterone and clinical menstruation can come.