title: Cervical collagen is reduced in non-pregnant women with a history of cervical insufficiency and a short cervix.
abstract: BACKGROUND
  Preterm cervical shortening and cervical insufficiency may be caused by a constitutional weakness of the cervix. The aim of this study was to assess the cervical collagen concentration in non-pregnant women with a history of cervical insufficiency or of a short cervix in the second trimester of pregnancy.
  
  
  METHODS
  In this case-control study we included non-pregnant women one year or more after pregnancy: 55 controls with a history of normal delivery; 27 women with a history of cervical insufficiency; and 10 women with a history of a short cervix (<5th percentile) and 10 women with a history of a long cervix (>95th percentile) at gestational weeks 18-20. We obtained biopsies (3 × 3-4 mm) from the ectocervix and determined the collagen concentration by measuring the hydroxyproline concentration.
  
  
  RESULTS
  Women with cervical insufficiency had lower collagen concentrations (63.5 ± 5.1%; mean ± SD) compared with controls (68.2 ± 5.4%; p = 0.0004); area under the ROC curve 0.73 (95% CI 0.62-0.84). A cut-off value at 67.6% collagen resulted in a positive likelihood ratio of 3.2, a sensitivity of 60%, and a specificity of 81%. Also, women with a short cervix in the second trimester had lower collagen concentrations in a non-pregnant state (62.1% ± 4.9%) compared with women with a long cervix (67.8% ± 5.0%; p = 0.02).
  
  
  CONCLUSIONS
  Both cervical insufficiency and a short cervix in the second trimester of pregnancy are associated with low cervical collagen concentrations in a non-pregnant state more than one year after pregnancy.
authors.affiliation: Department of Obstetrics and Gynecology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Iben
authors.initials: I
authors.lastname: Sundtoft
authors.affiliation: Clinic of Obstetrics and Gynecology, Rigshospitalet Copenhagen University Hospital, Copenhagen, Denmark.
authors.forename: Jens
authors.identifier: http://orcid.org/0000-0003-2838-2533
authors.initials: J
authors.lastname: Langhoff-Roos
authors.affiliation: Department of Obstetrics and Gynecology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Puk
authors.initials: P
authors.lastname: Sandager
authors.affiliation: Department of Obstetrics and Gynecology, The Regional Hospital Horsens, Horsens, Denmark.
authors.forename: Steffen
authors.initials: S
authors.lastname: Sommer
authors.affiliation: Department of Obstetrics and Gynecology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Niels
authors.initials: N
authors.lastname: Uldbjerg
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D002584:Cervix Uteri / Q000378:metabolism / Q000503:physiopathology*; D003094:Collagen / Q000378:metabolism*; D005260:Female; D006801:Humans; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D012372:ROC Curve; D012680:Sensitivity and Specificity; D002581:Uterine Cervical Incompetence / Q000503:physiopathology*
chemical_list: D003094:Collagen
keywords: Uterine cervix; cervical incompetence; cervical insufficiency; cervical length; collagen; hydroxyproline; prematurity; preterm birth