title: Sonographic cervical length, vaginal bleeding, and the risk of preterm birth.
abstract: OBJECTIVE
  We sought to evaluate the contributions of vaginal bleeding and cervical length to the risk of preterm birth.
  
  
  METHODS
  This was a secondary analysis of a cohort study designed to study predictors of preterm birth. The study included 2988 women with singleton gestations. Women underwent midtrimester transvaginal ultrasound assessment of cervical length and were queried regarding first- and second-trimester vaginal bleeding.
  
  
  RESULTS
  There was a significant second-order relation between cervical length and preterm birth (P < .001, P = .005). Women with vaginal bleeding were at higher risk of preterm birth (odds ratio, 1.5; 95% confidence interval, 1.3-2.0). There was a significant interaction between cervical length and vaginal bleeding (P = .015). After accounting for cervical length and interaction, the adjusted odds ratio for vaginal bleeding and preterm birth was 4.8 (95% confidence interval, 1.89-12.4; P = .001).
  
  
  CONCLUSIONS
  The magnitude of risk of preterm birth associated with sonographic cervical length depends on a woman's history of first- and second-trimester vaginal bleeding.
authors: Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Pittsburgh Medical Center, Pittsburgh, PA, USA.
authors: Devon M
authors: DM
authors: Ramaeker
authors: Hyagriv N
authors: HN
authors: Simhan
mesh_terms: D000293:Adolescent; D000328:Adult; D054791:Cervical Length Measurement; D002584:Cervix Uteri / Q000000981:diagnostic imaging*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D047928:Premature Birth / Q000453:epidemiology*; D012306:Risk; D016216:Ultrasonography, Prenatal; D014592:Uterine Hemorrhage / Q000453:epidemiology*; D055815:Young Adult