PGE2 is an effective agent for cervical ripening. It is most effective when administered intravaginally. Patients with unfavorable cervices who begin labor during cervical ripening have greater gestational ages, more baseline uterine activity, more initial uterine activity in response to PGE2, and lesser cesarean delivery rate than those patients who do not begin labor during cervical ripening. However, PGE2 should not be continued or administered when the patient is in active labor because it leads to unacceptable rates of hyperstimulation. Unfortunately, cervical ripening with PGE2 has little or no effect on the overall cesarean delivery rate.