title: The association between cervical dysplasia, a short cervix, and preterm birth.
abstract: OBJECTIVE
  We sought to determine whether cervical dysplasia in the absence of an excisional procedure is associated with an increased risk of preterm birth (PTB) and whether that risk is independent of the presence of a short cervix.
  
  
  METHODS
  This is a cohort study including women with a singleton pregnancy who underwent routine cervical length assessment between 18-23 6/7 weeks of gestation, stratified by cervical dysplasia (ie, no prior dysplasia, prior dysplasia but no excisional procedure, or prior excisional procedure). The frequency of a short cervix (≤2.5 cm) and PTB were compared between groups and multivariable analyses were performed to identify whether: (1) dysplasia alone or a prior excisional procedure was associated with PTB; and (2) whether these factors remained independently associated with PTB after adjusting for the presence of a short cervix.
  
  
  RESULTS
  Of the 18,528 women who met inclusion criteria, 3023 (16.3%) had prior dysplasia alone and 1356 (7.3%) had a prior excisional procedure. The frequency of a short cervix for women without dysplasia, with prior dysplasia alone, or with a prior excisional procedure was 0.8%, 1.0%, and 2.2%, respectively (P < .001). The frequency of PTB, respectively, was 6.4%, 6.5%, and 8.4% (P < .001). After adjusting for potential confounding factors, prior excisional procedure but not prior dysplasia alone was associated with PTB.
  
  
  CONCLUSIONS
  Having a prior cervical excisional procedure but not dysplasia alone is associated with an increased risk of PTB. This association is independent of the presence of a short cervix.
authors.affiliation: Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Feinberg School of Medicine, Northwestern University, Chicago, IL. Electronic address: emily-miller-1@northwestern.edu.
authors.forename: Emily S
authors.initials: ES
authors.lastname: Miller
authors.affiliation: Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Feinberg School of Medicine, Northwestern University, Chicago, IL.
authors.forename: Allie
authors.initials: A
authors.lastname: Sakowicz
authors.affiliation: Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Feinberg School of Medicine, Northwestern University, Chicago, IL.
authors.forename: William A
authors.initials: WA
authors.lastname: Grobman
mesh_terms: D000328:Adult; D054791:Cervical Length Measurement; D002584:Cervix Uteri / Q000002:abnormalities / Q000000981:diagnostic imaging* / Q000601:surgery; D015331:Cohort Studies; D003127:Colposcopy; D004598:Electrosurgery / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D015999:Multivariate Analysis; D009929:Organ Size; D011247:Pregnancy; D047928:Premature Birth / Q000453:epidemiology*; D012044:Regression Analysis; D012189:Retrospective Studies; D012307:Risk Factors; D002578:Uterine Cervical Dysplasia / Q000453:epidemiology* / Q000601:surgery
keywords: cervical dysplasia; excisional procedure; loop electrosurgical excision procedure; preterm birth