Objectives This study evaluated a new quantitative fetal fibronectin (fFN) bedside test (10Q) for the prediction of sPTB in patients presenting with symptoms suggestive of threatened preterm labour.

Study design A blinded, prospective observational study of 125 symptomatic participants recruited through St. Thomas' Hospital antenatal day assessment unit and antenatal ward. Women underwent a qualitative fFN and a 10Q test between 22-35 weeks. Outcome measures were delivery within 14 days, and <37 weeks.

Results 32 (23.5%) had a positive test and 12 (9.6%) delivered within 14 days of testing. The overall rate of sPTB (<37) was 13.9% which increased progressively with increasing levels of fFN, with rates of 3.07%, 17.39%, 16.67%, 53.33% and 75% within the five categories (fFN 0-9, 10-49, 50-200, 200+, 500+) respectively. The 10Q added enhanced discrimination between high-risk and low-risk patients. 10Q <10ng/mL had a 100% negative predictive value and >200ng/mL produced a 46.7% PPV for delivery within 14 days of testing. Compared to the standard qualitative fFN threshold of ±50ng/mL, 10Q of >200ng/mL increased the positive likelihood ratio by a factor of two (8.02 V’s 3.99).

Conclusion 10Q enhances the prediction of SPTB in symptomatic women. Hence, high-risk women can be more accurately identified for targeted management.