Whether contractions start or not is not directly related to the fetus being in labor, and should not be used as a criterion for judgment. Therefore, the absence of labor at 39 weeks is not directly related to the ability to start, but also needs to be considered comprehensively. Hormonal changes in the pregnant woman’s body before labor can cause changes in the myometrium and uterine morphology. Before labor, the secretion of estrogen, progesterone, and uterotonin in the pregnant woman’s body increases, and the sensitivity of the uterine myometrium increases, resulting in regular uterine contractions. So the mechanism of uterine contractions is due to the changes in hormone levels in the body, even if there is no fetus in the pelvis, contractions will still be initiated, and in some pregnant women, the head of the fetus in the pelvis occurs only after the initiation of contractions. In late pregnancy, the fetus enters the pelvis of the pregnant woman in a head-down, buttocks-up, full-body-curled position, and the primiparous woman usually enters the pelvis 1-2 weeks before labor, while the transient woman is relatively late, and usually enters the pelvis before labor or while labor is in progress. Therefore, pregnant women who are not pelvic at 39 weeks of pregnancy do not need to be overly nervous, they can first undergo obstetric examination, including ultrasonography, pelvic measurement, etc., to assess whether the position of the fetus is normal or not, especially pay attention to whether there is cephalopelvic disproportion, placenta praevia and other abnormalities. After eliminating the adverse factors, you can continue to observe and wait for labor, and you can also move appropriately, which is beneficial for the fetus to enter the pelvis.