Cervical ripening after nitric oxide

who respond poorly to such therapy. New approaches, such as the use of cytokines, antigestagens and relaxin continue to be explored and to these can now be added NO donors. A long-cherished dream of clinicians has been to achieve such a high degree of cervical ripeness before the onset of labour, that mothers only require a short period of myometrial contractions to complete cervical dilation. We might even dream of improving on spontaneous labour. In this regard NO donors, whether alone or in combination with other therapies, would seem to represent an exciting new prospect. On the other hand, the clinical subjects which may yet offer the most fertile field of investigation are those who respond poorly to therapies which are usually highly reliable. There is, for instance, a hard core of mothers whose cervices stubbornly resist local application of PGE2. This suggests that while PGE2 may be a crucial component in cervical ripening perhaps, as Kelly (1994) has suggested, by dilating and increasing the permeability to leukocytes of the cervical vasculature, that effect may be futile in the absence of other factors, such as chemokines and neutrophils. A clearer picture of the biology of cervical ripening is steadily emerging. Although the jigsaw is still far from complete, NO seems certain to be one of the pieces.