If the endometrium is 13mm thick and does not have menstruation, the cause should be clarified first, which may be caused by pregnancy, disease or mental factors, etc. It is recommended to consult a doctor to find out the cause and under the guidance of the doctor to carry out observation, medication or surgical treatment. 1. Pregnancy: In the early stage of pregnancy, the level of estrogen and progesterone in the body increases significantly, which may cause the endometrial lining of the uterus to be as thick as 13mm and no menstruation. You can go to the hospital for blood HCG test and other clear, determine the pregnancy should be regular pregnancy checks. 2. Disease factors: Some diseases, such as endometrial polyps, may cause the endometrium to be as thick as 13mm, which may also affect menstruation and lead to absence of menstruation, which should be promptly carried out under the guidance of the doctor under the supervision of hysteroscopic endometrial polypectomy. 3. Psychological factors: If a woman is overly anxious and mentally stressed, it may cause endocrine disorders, leading to abnormal endometrial thickening of up to 13mm and no menstruation. It can be regulated through psychological counseling, and if necessary, the use of drugs such as progesterone under the guidance of a doctor for treatment, after stopping the drug, it may cause withdrawal bleeding in order to play the role of medicated scraping. In addition, the endometrial thickness of 13mm does not come to menstruation, may also be seen in other reasons, it is recommended to timely consultation to identify the causes, under the guidance of the doctor active treatment.