Physiology of cervical ripening and dilatation

Maturation of the cervix is the result of a coordinated biochemical process , which at least initially is independent of uterine contractions. During m aturation, water is retained within the cervical tissue with reorganization of collagen fibrils. Humoral mediators such as prostaglandins,estrogen,and nitric oxide activate proteases,which digest collagen matrix. An abacteria l or bacterial inflammatory reaction accelerates this process. Invading inf lammatory cells release cytokines, nitric oxide, and proteases, which contr ibute to the loosening of the collagen structure. Finally,the mechanical influence of contractions results in dilatation of t he cervix. In cases of early maturation of the cervix, this cascade of even ts is initiated prematurely and is irreversible so that the cervix loses it s function as a closure and support structure at the lower end of the uteru s.