title: The significance of a positive fetal fibronectin in the setting of a normal cervical length in twin pregnancies.
abstract: 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.
authors.affiliation: Department of Obstetrics, Gynecology, and Reproductive Science, Mount Sinai School of Medicine, New York, New York, USA. nfox@mfmnyc.com
authors.forename: Nathan S
authors.initials: NS
authors.lastname: Fox
authors.forename: Andrei
authors.initials: A
authors.lastname: Rebarber
authors.forename: Ashley S
authors.initials: AS
authors.lastname: Roman
authors.forename: Chad K
authors.initials: CK
authors.lastname: Klauser
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Saltzman
mesh_terms: D000328:Adult; D054791:Cervical Length Measurement; D015331:Cohort Studies; D005260:Female; D005353:Fibronectins / Q000032:analysis*; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D011237:Predictive Value of Tests; D011247:Pregnancy; D011248:Pregnancy Complications; D011256:Pregnancy Outcome; D059285:Pregnancy, Twin; D047928:Premature Birth / Q000453:epidemiology*; D012189:Retrospective Studies; D012307:Risk Factors
chemical_list: C403421:FFN protein, human; D005353:Fibronectins