The significance of a positive fetal fibronectin in the setting of a normal cervical length in twin pregnancies

Nathan S. Fox, Andrei Rebarber, Ashley S. Roman, Chad K. Klauser, Daniel H. Saltzman

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5 Scopus citations


To estimate the risk of preterm birth in asymptomatic women with twin pregnancies with a normal cervical length (CL) and a positive fetal fibronectin (fFN), we reviewed a retrospective cohort of twin pregnancies delivered in our practice from 2005 to 2010. Patients were screened from 22 to 32 weeks with CL and fFN at 2- to 4-week intervals. We examined 244 patients with twin pregnancies and a normal CL (>25 mm) between 22 and 32 weeks and compared outcomes based on the fFN result. Fourteen (5.7%) patients had a positive fFN and 230 (94.3%) patients had a negative fFN. Positive fFN was associated with an increased the risk of spontaneous preterm birth < 37 weeks (85.7% versus 38.3%, p=0.001), < 35 weeks (50% versus 11.8%, p< 0.001), < 34 weeks (35.7% versus 6.9%, p< 0.001), and < 32 weeks (21.4% versus 2.2%, p< 0.001). On adjusted analysis, a positive fFN was independently associated with preterm birth < 32 weeks (odds ratio 6.8, 95% confidence interval 1.42, 32.2) and gestational age at delivery (p=0.001). In the setting of a normal CL, a positive fFN is significantly associated with preterm birth in asymptomatic twin pregnancies. Contingency model screening of fFN in asymptomatic twin pregnancies solely based on CL evaluation may fail to identify a cohort of at-risk patients.

Original languageEnglish
Pages (from-to)267-271
Number of pages5
JournalAmerican Journal of Perinatology
Issue number4
StatePublished - 2012


  • cervical length
  • fetal fibronectin
  • preterm birth
  • twins


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