New approaches to the prediction of preterm delivery.

Current approaches to the detection of patients at risk for preterm delivery (PTD) have focused on the diagnosis of preterm labor. However, these approaches are complicated by treatment biases and our inability to convincingly differentiate preterm labor from Braxton-Hicks contractions. Moreover, preterm labor with intact membranes accounts for only one-half of all spontaneous PTDs since uterine contractions follow preterm premature rupture of the membranes (PROM) in an additional 50% of cases. Clinical dogma holds that the prevention of PTD requires the early detection of at risk patients. However, clinical indicators of PTD risk including cervical change, uterine contractions, vaginal bleeding, maternal demographic featuers and obstetrical history have poor sensitivity and/or specificity. Fortunately, an improved understanding of the association between preterm parturition and cervical, chorionic and decidual extracellular matrix degradation has led to a number of promising new biochemical indices of the proteolytic processes leading to PTD. These include measurement of serum collagenase activity and assessment of cervico-vaginal granulocyte elastase and oncofetal fibronectin levels. It remains to be seen, however, whether an improved detection of patients at risk will lead to a reduction in the occurrence of PTD.