It is uncertain how many days it usually takes to induce labor. The duration of induction is not the same for different methods of induction or for different pregnant women. The method of labor induction is usually determined by the condition of the cervix, which is not uniformly ripe from one pregnancy to the next. Usually the cervical score less than 7 pregnant women, need to promote cervical ripening, and then according to the contractions and fetal conditions to decide whether to strengthen the contractions to induce labor; for cervical ripening of pregnant women, usually can be directly drip oxytocin to strengthen the contractions to induce labor. Currently, the most common methods of promoting cervical ripening include the placement of a dilatation balloon in the cervix and the use of vaginal prostaglandin preparations. The number of days to induce labor cannot be determined because different pregnant women respond differently to the effects of prostaglandin preparations, cervical balloons, and oxytocin. Pregnant women who need to terminate their pregnancy when the time for labor has come need to be examined and evaluated by a doctor and choose the most suitable way to induce labor in order to achieve the best results.