title: The rate of cervical change and the phenotype of spontaneous preterm birth.
abstract: OBJECTIVE
  Preterm birth is classified by the presence of uterine contractions and/or amniorrhexis at clinical presentation. This classification does not include prior cervical change. We hypothesized that the rate of cervical shortening before preterm birth would not differ according to clinical presentation.
  
  
  METHODS
  We analyzed data from a completed study of paired cervical ultrasound measurements to test our hypothesis. Cervical ultrasound measurements obtained 4 weeks apart in the second trimester were related to gestational age and clinical presentation at birth.
  
  
  RESULTS
  Of 2521 eligible women, 128 were delivered after preterm labor and 106 after preterm membrane rupture; 89 delivered preterm for a medical or obstetrical indication; 2198 delivered at term. The rate of change was similar in women who presented with preterm labor (-0.96 mm/week) and preterm ruptured membranes (-0.82 mm/week).
  
  
  CONCLUSIONS
  Cervical shortening occurs at the same rate before spontaneous preterm birth, regardless of presentation.
authors.affiliation: Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, The Ohio State University College of Medicine, Columbus, OH, USA.
authors.forename: Jay D
authors.initials: JD
authors.lastname: Iams
authors.forename: Deborah
authors.initials: D
authors.lastname: Cebrik
authors.forename: Courtney
authors.initials: C
authors.lastname: Lynch
authors.forename: Nicholas
authors.initials: N
authors.lastname: Behrendt
authors.forename: Anita
authors.initials: A
authors.lastname: Das
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D020070:Cervical Ripening / Q000235:genetics*; D002584:Cervix Uteri / Q000000981:diagnostic imaging*; D015331:Cohort Studies; D005260:Female; D047109:Fetal Development / Q000235:genetics / Q000502:physiology; D005322:Premature Rupture of Fetal Membranes / Q000000981:diagnostic imaging / Q000235:genetics*; D006801:Humans; D007231:Infant, Newborn; D008991:Monitoring, Physiologic / Q000379:methods; D010641:Phenotype; D011237:Predictive Value of Tests; D011247:Pregnancy; D011256:Pregnancy Outcome; D011262:Pregnancy Trimester, Second; D047928:Premature Birth / Q000000981:diagnostic imaging* / Q000235:genetics*; D011295:Prenatal Care / Q000379:methods; D011446:Prospective Studies; D012016:Reference Values; D047929:Term Birth; D013997:Time Factors; D016216:Ultrasonography, Prenatal; D014590:Uterine Contraction / Q000502:physiology; D055815:Young Adult