Quantitative fetal fibronectin (qfFN) testing has demonstrated accuracy at predicting sPTB in high-risk asymptomatic women (previous preterm birth or late miscarriage). It is not known whether qfFN has predictive accuracy in pregnancy after cervical surgery (a potentially different risk mechanism). This study compares the predictive value of qfFN in these two high-risk groups.Methods
A prospective blinded secondary analysis of a larger observational study of cervicovaginal fluid fFN concentration (ng/ml) in asymptomatic women using rapid bedside 10q qfFN testing (Hologic™). Prediction of sPTB using qfFN concentrations in primiparous women who had undergone at least one surgical cervical procedure (n = 319) were compared with prediction in women who had one previous spontaneous preterm birth or late miscarriage (n = 236). Iatrogenic deliveries before the gestation of interest were excluded.Results
The rate of sPTB <37 weeks in cervical surgery group was 4.1% compared with 19.4% in previous sPTB group. ROC curves for prediction of sPTB <34 and <37 weeks’ were comparable in both groups (34 weeks: 0.98 vs. 0.74, p = 0.05; 37 weeks: 0.604 vs 0.659, p = 0.62). An fFN concentration of >200 ng/ml had comparable positive prediction for sPTB <37 weeks’ in the cervical surgery group vs. previous sPTB group (42.9%; 95% CI 9.9–81.6 vs 54.5%; 95% CI 32.2–75.6) whilst negative prediction remained high for both groups (96.8% 95% CI 94.1–98.4 vs. 84.3% 95% CI 78.6–88.9).Conclusions
Prediction of sPTB using qfFN in women with cervical surgery is useful, and has comparative accuracy to that in women with a history of sPTB.