Cervical maturation and labor induction

Abstract

Cervical maturation is one of the key events in the process of labor, either at term or preterm. The mechanisms involved in cervical ripening start early in pregnancy and increase near parturition. The main changes occur in the cervical connective tissue, mainly the extracellular matrix. They include disorganization of collagen network, increase in hyaluronic acid, increased water content and changes in the proteoglycan content, leading to dramatic changes in the consistency of the cervix.
The pharmacologic control of the cervical ripening process is of major interest, either to allow labor induction in case of an unfavorable cervix, or to prevent preterm delivery in case of premature cervical shortening.
Many substances are known to play a role in the physiologic and pathologic processes of cervical ripening: prostaglandins, relaxin, nitric oxide and inflammatory cytokines may induce cervical priming whereas progesterone play an inhibitory role in the process of cervical ripening and labor induction.
Based on these pathophysiological data, several compounds and/or interventions have been proposed to induce or conversely to prevent cervical ripening and labor with uneven success. Data from recent studies on cervical maturation and labor induction in case of unripe cervix are presented in this review.