A thinner lower uterine segment myometrium of 1mm is more risky. A lower segment of the uterus with a thinner base of 1mm is usually seen in late pregnancy with a history of cesarean section, in which case the risk of delivery is higher. The risk of labor is related to factors such as uterine elasticity and location of weakness. 1. Uterine wall elasticity: patients with a history of cesarean section have poor elasticity of the scar at the cesarean incision in the lower part of the uterus, and the risk of rupture is higher in a second pregnancy with a thickness of 1mm, and there is often a lack of symptoms of rupture with aura, and the physical signs are not obvious. 2. The location of the weak point: if the weak point is near the uterine blood vessels on both sides, the risk of uterine rupture during labor will lead to acute hemorrhage, which is very dangerous. For pregnant women with a history of cesarean section, it is recommended that they under the guidance of a doctor should undergo labor checkups on a regular basis and seek immediate medical attention if any abnormality occurs, so as not to jeopardize the life of the pregnant woman and the fetus.