There are no clear statistics on how long it takes for contractions to open the uterus. At the same time, because of the different nature of contractions, the mouth of the uterus may not open after contractions, which needs to be analyzed in different situations. If the pregnant woman has not reached the expected date of labor, it is usually considered false contractions, manifested by the inconsistent frequency of contractions, short duration, long intervals and irregular; the degree of contraction is sometimes strong and sometimes weak; it is not accompanied by shortening of the cervical canal, dilatation of the mouth of the uterus and other cervical morphology changes, usually after rest or change position false contractions can be alleviated on their own, at this time, the mouth of the uterus will not be open. For full-term pregnant women, the contractions are regular contractions of the uterus, the specific contractions how long the mouth of the uterus is open varies from person to person, can not be generalized, but along with the regular contractions, the mouth of the uterus is dilated with certain characteristics. When a pregnant woman is about to go into labor, the intensity of the contractions will gradually change from weak to strong, in order to promote the delivery of the fetus. The contractions are initially about once every 30 minutes and last about 20 seconds. When they gradually start to occur once every 5 minutes or even less, it is usually a sign that the uterine opening is gradually beginning to dilate. Therefore, pregnant women who experience contractions should consult a doctor in a timely manner. If the contraction occurs when the woman is not in full-term labor, it is often considered to be a false contraction, and generally does not require any special treatment; if the contraction occurs when the woman is about to give birth, she needs to consult a doctor in a timely manner, and make the relevant preparations for the delivery.