title: Circulating relaxin and cervical length in midpregnancy are independently associated with spontaneous preterm birth.
abstract: OBJECTIVE
  We sought to examine associations among serum relaxin levels, cervical length, and spontaneous preterm birth (sPTB).
  
  
  METHODS
  We conducted a case-control study within a cohort of 1080 singleton pregnant women. In all, 38 women (3.5%) delivered spontaneously preterm (< 37 completed weeks of gestation). Relaxin was measured in serum in gestational weeks 12 and 19, cervical length only in week 19. Associations to sPTB were evaluated by logistic regression analysis and receiver operating characteristic curves.
  
  
  RESULTS
  Cervical length and relaxin in week 19, but not week 12 were associated to sPTB. There were no correlations between cervical length and relaxin level in week 12 (controls: Spearman rho: -0.07, P = .45; cases: Spearman rho: -0.07, P = .72) or week 19 (controls: Spearman rho: -0.03, P = .77; cases: Spearman rho: 0.04, P = .84).
  
  
  CONCLUSIONS
  There were no correlation between relaxin concentrations and the cervical length, indicating that relaxin is probably not the cause of preterm shortening of the cervix.
authors.affiliation: Y Research Laboratory, Department of Gynecology and Obstetrics, Aarhus University Hospital, Skejby, DK-8200 Aarhus N. Denmark. puk@dadlnet.dk
authors.forename: Puk
authors.initials: P
authors.lastname: Sandager
authors.forename: Niels
authors.initials: N
authors.lastname: Uldbjerg
authors.forename: Tine Brink
authors.initials: TB
authors.lastname: Henriksen
authors.forename: Laura T
authors.initials: LT
authors.lastname: Goldsmith
authors.forename: Poul
authors.initials: P
authors.lastname: Thorsen
authors.forename: Gerson
authors.initials: G
authors.lastname: Weiss
authors.forename: Ida
authors.initials: I
authors.lastname: Vogel
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D020070:Cervical Ripening / Q000502:physiology*; D002584:Cervix Uteri / Q000000981:diagnostic imaging* / Q000503:physiopathology; D005260:Female; D006801:Humans; D011237:Predictive Value of Tests; D011247:Pregnancy; D011262:Pregnancy Trimester, Second / Q000097:blood; D047928:Premature Birth / Q000097:blood* / Q000000981:diagnostic imaging* / Q000453:epidemiology; D012372:ROC Curve; D012065:Relaxin / Q000097:blood*; D012307:Risk Factors; D016216:Ultrasonography, Prenatal
chemical_list: D012065:Relaxin