Biophysical and biochemical screening for the risk of preterm labor.

Preterm birth is the leading cause of perinatal morbidity and mortality in developed nations. The heterogeneous causes of spontaneous preterm birth make prediction and prevention difficult. Recently developed biochemical and biophysical tests add significantly to clinicians' ability to evaluate and treat women at risk for spontaneous preterm birth. The primary importance of transvaginal cervical sonography and cervicovaginal fetal fibronectin lies in the high negative predictive values of the tests for reducing preterm delivery risk. Cervical length may be useful in identifying women who are candidates for cervical cerclage or progesterone therapy for preterm birth prevention. Together, cervical length and fibronectin can be used in the triaging of women symptomatic for preterm labor.