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.