Combined fetal fibronectin and cervical length and spontaneous preterm birth in asymptomatic triplet pregnancies
Nathan S Fox1, Andrei Rebarber, Ashley S Roman
1Maternal Fetal Medicine Associates, PLLC, New York, NY 10128, USA. nfox@mfmnyc.com
Objective:
To estimate the association between fetal fibronectin (fFN), cervical length (CL), and spontaneous preterm birth (SPTB) in asymptomatic women with triplet pregnancies.
Study Design:
A cohort of 39 consecutive women with triplet pregnancies managed in one Maternal-Fetal medicine practice from 2005-2011 was analyzed. Combined fFN and CL testing was performed every 2 weeks from 22-32 weeks. A short CL was defined as ≤ 20 mm.
Results:
A positive fFN was significantly associated with SPTB <28 weeks, <30 weeks, <32 weeks, and <34 weeks. A short CL was significantly associated with SPTB <32 weeks. On combined testing, having both tests positive was associated with the highest likelihood of SPTB at all gestational ages. As a screening test for SPTB <32 weeks, having both a positive fFN and a short CL had a sensitivity of 62.5%, specificity of 90%, positive predictive value of 62.5%, negative predictive value of 90%, positive likelihood ration of 2.98 and negative likelihood ratio of 0.88. Combined fFN and CL outperformed fFN alone, CL alone, or either test being positive alone.
Conclusions:
In asymptomatic women with triplet pregnancies, fFN and CL are each significantly associated with SPTB. For the prediction of SPTB, combined fFN and CL testing outperforms either test alone.
