The value of combined cervical length measurement and fetal fibronectin testing to predict spontaneous preterm birth in asymptomatic high-risk women

OBJECTIVES: To determine the value of the combined use of fetal fibronectin (fFN) testing and transvaginal ultrasound measurement of cervical length (CL) for prediction of preterm birth (PTB) in asymptomatic high-risk women. METHODS: One hundred and forty-seven asymptomatic women at high-risk of PTB were referred to specialist antenatal clinics and underwent CL and fFN testing over a 12-month period. Women had both tests undertaken between 22(+0) and 30(+0) weeks' gestation, on one or more occasions. RESULTS: In those who labored spontaneously (n = 132), positive fFN and CL ≤ 25 mm was associated with a 53% risk of PTB at < 37(+0) weeks' gestation, compared to a 10% risk in those with a negative fFN and CL > 25 mm. With a known CL, the addition of positive fFN yielded significant hazard ratios regardless of CL (CL > 25 mm-HR 2.78, CL ≤ 25 mm-HR 3.14, p < 0.05). The hazard ratios were insignificant when CL results were added to a known fFN. CONCLUSIONS: In high-risk asymptomatic women, fFN may be used as a primary screening tool with CL measurement being reserved for those with a positive fFN result. Further prospective studies are needed to confirm our findings.