Usually the endometrium of the uterus is 7mm and menstruation usually occurs after about 1 more week. Usually menstruation is possible after the endometrium gradually thickens to more than 1cm. Due to the different physical qualities of each woman, the thickness of the endometrium varies during menstruation. For example, in some women with a thin endometrium, the endometrium may not reach 1cm before menstruation occurs. Therefore, you cannot rely solely on the thickness of the endometrium to predict how soon you will have your period. If you have irregular periods or are affected by other abnormalities, this may also affect the time of menstruation. Some women with regular periods may show delayed periods if the endometrium stops thickening at 7mm, and then the cause needs to be identified and treated. The first step is to check blood and urine HCG to rule out pregnancy. The common causes of delayed menstruation after pregnancy is ruled out are mental and psychological factors, such as nervousness, stressful work, and poor mood, etc. Usually, no special treatment is needed, and progestin-like drugs can be given to promote menstruation. If there is regular delayed menstruation and the endometrium never thickens, it is necessary to check female sex hormone six and thyroid function because there will be some women who have delayed menstruation due to progesterone deficiency, polycystic ovary syndrome, thyroid function abnormalities, hyperprolactinemia, etc. The growth rate of endometrium becomes slower and affects the time of menstruation. 1. Progesterone deficiency: For such patients, they can generally be treated with 2. polycystic ovary syndrome: manifested as elevated androgens or luteinizing hormone, requiring short-acting oral contraceptive substitution therapy such as ethinyl estradiol cyproterone tablets to adjust the menstrual cycle as prescribed by the doctor; 3. thyroid function abnormalities: firstly, thyroid function should be controlled within the normal range and treated with hormone supplementation; 4. hyperprolactinemia: causing endometrial Insufficient thickening, need to use bromocriptine mesylate medication according to medical prescription.