title: Quantitative fetal fibronectin testing in combination with cervical length measurement in the prediction of spontaneous preterm delivery in symptomatic women.
abstract: To evaluate whether in symptomatic women, the combination of quantitative fetal fibronectin (fFN) testing and cervical length (CL) improves the prediction of preterm delivery (PTD) within 7 days compared with qualitative fFN and CL.
  
  
  
  Post hoc analysis of frozen fFN samples of a nationwide cohort study.
  
  
  
  Ten perinatal centres in the Netherlands.
  
  
  
  Symptomatic women between 24 and 34 weeks of gestation.
  
  
  
  The risk of PTD <7 days was estimated in predefined CL and fFN strata. We used logistic regression to develop a model including quantitative fFN and CL, and one including qualitative fFN (threshold 50 ng/ml) and CL. We compared the models' capacity to identify women at low risk (<5%) for delivery within 7 days using a reclassification table.
  
  
  
  Spontaneous delivery within 7 days after study entry.
  
  
  
  We studied 350 women, of whom 69 (20%) delivered within 7 days. The risk of PTD in <7 days ranged from 2% in the lowest fFN group (<10 ng/ml) to 71% in the highest group (>500 ng/ml). Multivariable logistic regression showed an increasing risk of PTD in <7 days with rising fFN concentration [10-49 ng/ml: odds ratio (OR) 1.3, 95% confidence interval (95% CI) 0.23-7.0; 50-199 ng/ml: OR 3.2, 95% CI 0.79-13; 200-499 ng/ml: OR 9.0, 95% CI 2.3-35; >500 ng/ml: OR 39, 95% CI 9.4-164] and shortening of the CL (OR 0.86 per mm, 95% CI 0.82-0.90). Use of quantitative fFN instead of qualitative fFN resulted in reclassification of 18 (5%) women from high to low risk, of whom one (6%) woman delivered within 7 days.
  
  
  
  In symptomatic women, quantitative fFN testing does not improve the prediction of PTD within 7 days compared with qualitative fFN testing in combination with CL measurement in terms of reclassification from high to low (<5%) risk, but it adds value across the risk range.
  
  
  
  Quantitative fFN testing adds value to qualitative fFN testing with CL measurement in the prediction of PTD.
authors.affiliation: Obstetrics and Gynaecology, Academic Medical Centre, Amsterdam, the Netherlands. m.m.bruijn@amc.uva.nl.
authors.forename: Mmc
authors.initials: M
authors.lastname: Bruijn
authors.affiliation: Clinical Chemistry and Haematology, University Medical Centre Utrecht, Utrecht, the Netherlands.
authors.forename: J Y
authors.initials: JY
authors.lastname: Vis
authors.affiliation: Obstetrics and Gynaecology, Catharina Hospital, Eindhoven, the Netherlands.
authors.forename: F F
authors.initials: FF
authors.lastname: Wilms
authors.affiliation: Obstetrics and Gynaecology, Academic Medical Centre, Amsterdam, the Netherlands.
authors.forename: M A
authors.initials: MA
authors.lastname: Oudijk
authors.affiliation: Obstetrics and Gynaecology, University Medical Centre Utrecht, Utrecht, the Netherlands.
authors.forename: A
authors.initials: A
authors.lastname: Kwee
authors.affiliation: Obstetrics and Gynaecology, Máxima Medical Centre, Veldhoven, the Netherlands.
authors.forename: M M
authors.initials: MM
authors.lastname: Porath
authors.affiliation: Obstetrics and Gynaecology, Máxima Medical Centre, Veldhoven, the Netherlands.
authors.forename: G
authors.initials: G
authors.lastname: Oei
authors.affiliation: Obstetrics and Gynaecology, University Hospital Maastricht, Maastricht, the Netherlands.
authors.forename: Hcj
authors.initials: H
authors.lastname: Scheepers
authors.affiliation: Obstetrics and Gynaecology, University Hospital Maastricht, Maastricht, the Netherlands.
authors.forename: Mea
authors.initials: M
authors.lastname: Spaanderman
authors.affiliation: Obstetrics, Leiden University Medical Centre, Leiden, the Netherlands.
authors.forename: Kwm
authors.initials: K
authors.lastname: Bloemenkamp
authors.affiliation: Obstetrics, Leiden University Medical Centre, Leiden, the Netherlands.
authors.forename: M C
authors.initials: MC
authors.lastname: Haak
authors.affiliation: Obstetrics and Gynaecology, Radboud University Medical Centre, Nijmegen, the Netherlands.
authors.forename: A C
authors.initials: AC
authors.lastname: Bolte
authors.affiliation: Obstetrics and Gynaecology, Radboud University Medical Centre, Nijmegen, the Netherlands.
authors.forename: Fpha
authors.initials: F
authors.lastname: Vandenbussche
authors.affiliation: Obstetrics and Gynaecology, Radboud University Medical Centre, Nijmegen, the Netherlands.
authors.forename: M D
authors.initials: MD
authors.lastname: Woiski
authors.affiliation: Obstetrics and Gynaecology, VU University Medical Centre, Amsterdam, the Netherlands.
authors.forename: C J
authors.initials: CJ
authors.lastname: Bax
authors.affiliation: Obstetrics and Gynaecology, Erasmus Medical Centre, Rotterdam, the Netherlands.
authors.forename: Jmj
authors.initials: J
authors.lastname: Cornette
authors.affiliation: Obstetrics and Gynaecology, Erasmus Medical Centre, Rotterdam, the Netherlands.
authors.forename: J J
authors.initials: JJ
authors.lastname: Duvekot
authors.affiliation: Obstetrics and Gynaecology, Isala Clinics, Zwolle, the Netherlands.
authors.forename: Bwa
authors.initials: B
authors.lastname: Nij Bijvanck
authors.affiliation: Obstetrics and Gynaecology, Isala Clinics, Zwolle, the Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: van Eyck
authors.affiliation: Obstetrics and Gynaecology, University Medical Centre Groningen, Groningen, the Netherlands.
authors.forename: Mtm
authors.initials: M
authors.lastname: Franssen
authors.affiliation: Obstetrics and Gynaecology, University Medical Centre Groningen, Groningen, the Netherlands.
authors.forename: K M
authors.initials: KM
authors.lastname: Sollie
authors.affiliation: Obstetrics and Gynaecology, Academic Medical Centre, Amsterdam, the Netherlands.
authors.forename: Jam
authors.initials: J
authors.lastname: van der Post
authors.affiliation: Clinical Epidemiology, Biostatistics and Bioinformatics, Academic Medical Centre, Amsterdam, the Netherlands.
authors.forename: Pmm
authors.initials: P
authors.lastname: Bossuyt
authors.affiliation: Clinical Research Unit, Academic Medical Centre, Amsterdam, the Netherlands.
authors.forename: B C
authors.initials: BC
authors.lastname: Opmeer
authors.affiliation: Obstetrics and Gynaecology, Academic Medical Centre, Amsterdam, the Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Kok
authors.affiliation: The Robinson Institute, School of Paediatrics and Reproductive Health, University of Adelaide, Adelaide, SA, Australia.
authors.forename: Bwj
authors.initials: B
authors.lastname: Mol
authors.affiliation: Obstetrics and Gynaecology, Academic Medical Centre, Amsterdam, the Netherlands.
authors.forename: G-J
authors.initials: GJ
authors.lastname: van Baaren
mesh_terms: D054791:Cervical Length Measurement; D002584:Cervix Uteri / Q000737:chemistry; D015331:Cohort Studies; D005260:Female; D005353:Fibronectins; D006801:Humans; D007231:Infant, Newborn; D007752:Obstetric Labor, Premature; D011237:Predictive Value of Tests; D047928:Premature Birth
chemical_list: D005353:Fibronectins
keywords: Cervical length; prediction; pregnancy; preterm labour; quantitative fetal fibronectin