Fetal fibronectin in the cervicovaginal fluid of women with threatened preterm labour as a predictor of delivery before 34 weeks' gestation.

Fetal fibronectin (fFN) is an extracellular matrix protein found at the junction between fetal and maternal tissue. It has been hypothesized that fFN is released into cervicovaginal fluid prior to the onset of preterm labour and during episodes of threatened preterm labour (TPL). In the present study fFN was present in the cervicovaginal fluid of 31% (11/36) of patients with TPL. The presence of fFN was found to be predictive of delivery prior to 34 weeks' gestation in 36 patients presenting with TPL and intact membranes (sensitivity 100%, specificity 81%). Eleven patients had a positive fFN assay and 5 delivered before 34 weeks (positive predictive value (PPV) 46%). Twenty-five patients had a negative fFN result and none were delivered before 34 weeks (negative predictive value (NPV) 100%). Patients presenting with TPL who are fFN positive would be ideal candidates for intervention trials of tocolytics. It may be possible to delay or avoid immediate tocolysis and interhospital transfer in patients with a negative fFN immunoassay.