title: Time-related changes of cervical length as a predictor of labor onset within one week using transvaginal ultrasonography.
abstract: OBJECTIVE
  To assess the value of transvaginal cervical length (CL) measurement and funneling of the internal cervical os to predict the onset of spontaneous labor within one week.
  
  
  METHODS
  Observational prospective study.
  
  
  METHODS
  A total of 234 women who delivered after spontaneous onset of labor.
  
  
  METHODS
  CL was measured and the presence of funneling of the internal cervical os was recorded by transvaginal ultrasound examination.
  
  
  METHODS
  CL changes from 37 to 40 weeks of gestation as a one-point measurement, as well as the long-term (16-21 weeks to term or 37-40 weeks) and short-term (weekly from 37 to 40 weeks) differences in CL.
  
  
  RESULTS
  The one-point measurement of CL, with an optimum cut-off point of 25 mm [odds ratio (OR) 3.19; 95% confidence interval (CI) 2.01-5.05] and a decreased long-term CL (cervical shortening of 55% as an optimum cut-off point (OR 3.75; 95% CI 1.76-8.00) may predict the onset of spontaneous labor within one week. The likelihood of spontaneous labor within one week is high when funneling of the internal cervical os is present (OR 2.68; 95% CI 1.71-4.19).
  
  
  CONCLUSIONS
  Transvaginal CL measurement and observation of funneling of the internal cervical os are useful predictors of the onset of spontaneous labor.
authors.affiliation: Division of Obstetrics and Gynecology, Akita University Hospital, 1-1-1 Hondo, Akita, Japan. miurah@obgyn.med.akita-u.ac.jp
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Miura
authors.forename: Masaki
authors.initials: M
authors.lastname: Ogawa
authors.forename: Hideto
authors.initials: H
authors.lastname: Hirano
authors.forename: Toshinobu
authors.initials: T
authors.lastname: Tanaka
mesh_terms: D000293:Adolescent; D000328:Adult; D054791:Cervical Length Measurement; D020070:Cervical Ripening; D002584:Cervix Uteri / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007745:Labor Onset / Q000502:physiology*; D011237:Predictive Value of Tests; D011247:Pregnancy; D013997:Time Factors; D016216:Ultrasonography, Prenatal; D055815:Young Adult