The thickness of the lining of the uterus on the twelfth day after menstruation is about 1.0~1.2 centimeters. A woman’s normal menstrual period is mostly 2-8 days, the average is 3~5 days, and the 12th day after menstruation is about the 15th~17th day of the menstrual cycle, which belongs to the period of ovulation just after the ovulation period. At this time, the endometrial lining is mostly about 1.0~1.2 centimeters, which is most conducive for the fertilized egg to bed, and to increase the fertilization rate of pregnancy. Before menstruation comes soon, the lining may slowly grow to about 1.0~1.2 centimeters, and if there is no pregnancy, menstruation will come as the corpus luteum retreats. When menstruation has peeled off, the lining is in a thinner state, about 0.4 centimeters. Women’s endometrial thickness is with the follicle development, ovulation, corpus luteum formation, etc. will change, such as in the preparation for pregnancy, monitoring the follicle at the same time also pay attention to the thickness of the endometrial lining, whether the two are synchronized, and if there is any abnormality, go to the hospital in a timely manner, the professional doctor to give the relevant examination, to clarify the cause of the disease, targeted treatment.