Cervical ripening: Why we do what we do.

More than 20% of pregnant women have their labor induced and at least half of them will require cervical ripening due to an unfavorable starting cervical exam. The use of cervical ripening methods has been shown to decrease the risk of cesarean delivery when compared to initiating an induction with oxytocin in women with an unfavorable cervix. However, among the different cervical ripening methods themselves, while there may be differences in time to delivery and differences in the safety profile of different cervical ripening methods, there is no clear evidence that any one cervical ripening method reduces the risk of cesarean compared to another method. The objectives of this manuscript are to discuss the pathophysiology of cervical ripening including the biochemical processes that lead to cervical ripening; to review the different methods of cervical ripening including both mechanical and pharmacologic methods, and to evaluate the evidence and efficacy for different doses, routes, and techniques employed when using various cervical ripening methods.