The time it takes for the uterus to dilate from one finger to three fingers during labor varies from person to person, and is longer for primigravid women, generally no more than 20 hours, and for transient women, no more than 14 hours at the longest. Before the opening of the uterus three centimeters belongs to the incubation period of the first stage of labor, the incubation period is the slow stage of dilatation of the uterus, pregnant women in this stage should relax emotionally, eat more light, easy to digest food, pay attention to increase sleep. When pregnant women sleep and relax, the muscle ligaments of the whole body are looser, and the uterus opens faster during regular contractions. During the incubation period of the first stage of labor, if the pregnant woman is nervous, anxious, not eating or sleeping, it will seriously affect the speed of the opening of the mouth of the uterus.