[Rational use of fetal fibronectin in the evaluation of premature labor risk].

Objective: To better determined the usefulness of fetal fibronectin assay to identify patients at risk of premature delivery.
Subjects: 155 primiparous or multiparous patients presenting with single or twin pregnancies between 24 and 34 weeks and divided into 3 groups: high risk (70 patients), medium risk (35 patients), and low risk (50 patients) of premature delivery.
Main Outcome Measures: The occurrence of delivery in the 21 days following sampling and/or a premature delivery.
Results: Among the 50 patients in the low risk group, there was one false positive and no premature delivery. Among the 35 patients in the medium risk group, there was no single positive fetal fibronectin test and no premature delivery. Among the 70 patients in the high risk group, 14 had a premature rupture of the membranes with very strongly positive fetal fibronectin test and all were delivery prematurely, 11 within a period of less than 21 days. The remaining 56 patients presented a threat of premature delivery without rupture of membranes; 20 gave birth prematurely (prevalence: 35.7%). In patients with a negative fetal fibronectin test, those with positive fetal fibronectin test were significantly more likely to experience preterm birth (odds ration: 12; 95% confidence interval: 3.4 to 42.1; p = 0.001) or to deliver within 21 days (odds ratio: 29.9; 95% confidence interval: 13.3 to 243; p < 0.001).
Conclusion: Measurement of fetal fibronectin in cervico-vaginal secretions enabled us to define an authentic sub-group at high risk of premature delivery among patients presenting uterine contractions and changes in the cervix. In contrast, measurement of fetal fibronectin in cervico-vaginal secretions of patients with low and medium risk is not suitable, due to the low rate of premature delivery in these groups and the significant increase in the cost of pregnancy monitoring.