[Biochemical markers for preterm delivery (excepting markers of infection)]

Fetal fibronectin is an extracellular glycoprotein secreted at the maternal-fetal interface by the trophoblast. Fetal fibronectin testing may be useful in women with symptoms of preterm labor to identify those with negatives values and a reduced risk of preterm birth (NP 3). Fetal fibronectin could be either detected by cervical or vaginal sampling (NP 3). Concentrations of fetal fibronectin could be measured by an enzyme-linked immunosorbent assay or by a bedside dipstick technique (NP 3). There are numerous false-positive results in women with cervical dilatation, recent intercourse or cervical examination, and vaginal bleeding (NP 3). In most of the studies, a quantitative test was used with 50ng/ml as the cuttoff point for a positive results. There are no convincing data to recommend fetal fibronectin rather than cervical ultrasonography (and inversely), or to used these two tests together to predict preterm birth (NP 3). The choice should depend on the availability and the cost of each test. Other biochemical markers (salivary estriol or plasma CRH) are still under assessment and should not be used outside research protocols (NP 3).