The endometrium is around 6-8mm at the time of ovulation and will not exceed 1cm. It is not normal for the endometrium to exceed 1cm and 14mm. Since a thick endometrium is also a factor that prevents conception and can reduce the chances of pregnancy, it is important to have an endocrine hormone test to rule out high estrogen, which can cause persistent thickening of the endometrium. If the endometrium continues to grow before menstruation, take oral progestin for 3 months in the second half of the cycle, if possible. If the effect is not obvious, hysteroscopic endometrial scraping is recommended to determine the period of change of the lining, and medication and treatment will be administered according to the situation. Avoiding this can cause abnormal bleeding, increased menstrual flow, or even induce endometrial polyps.