The thinnest part of the uterine wall in the second trimester should not be less than 2-3 mm. if the thickness of the uterine wall is less than 2-3 mm, the risk of uterine rupture is higher and needs to be taken seriously. As the fetus grows and develops normally, the size of the uterus gradually increases and the uterine wall gradually becomes thinner. Although the thickness of the uterine wall in late pregnancy is affected by many factors, under normal circumstances, the uterine wall should not be less than 2-3mm, and if the uterine wall is particularly thin, there may be a risk of uterine rupture in the event of increased abdominal pressure, which may have a serious impact on the fetus and the pregnant woman. Therefore, it is recommended that pregnant women with a uterine wall thickness of less than 2-3 mm in late pregnancy should pay attention to the need to go to the hospital for regular checkups, go to the hospital immediately if they feel unwell to assess the general condition of the fetus, monitor the thickness of the uterus by ultrasonography, and choose the appropriate mode of delivery with the help of a specialized doctor to minimize the occurrence of adverse prognosis.