How long does it take for the cervical mucus plug to flow out varies greatly from one individual to another and is usually expelled 3-5 days before labor, but some pregnant women may start labor within 1-2 days. Due to the shortening of the cervical canal and the pressure of the anterior amniotic sac on the cervix, a mucus plug is formed in the cervical area before labor. Therefore, mucus plugs are discharged from the cervix as a sign of dilatation of the lower uterine segment and the cervix before labor. Since the maturity of the cervix varies from individual to individual, it is impossible to determine how long it will take for labor to begin based on the time of discharge of the cervical mucus plug. The onset of labor is a reliable sign before labor, and labor usually starts within 24-48 hours after the onset of labor. Depending on the individual pregnancy, the cervical mucus plug is usually expelled 3-5 days before labor, or even 1 week before clinical delivery. If the cervical mucus plug is expelled in combination with redness, labor usually begins within 1-2 days. If there is only cervical mucus plug but no redness, it can be observed for a few more days. In addition, the cervical mucus plug in late pregnancy should be distinguished from amniotic fluid; women are advised to keep their vulva clean.