title: Predictive value of transvaginal cervical length in triplet pregnancies for spontaneous preterm delivery at < or = 32 weeks.
abstract: OBJECTIVE
  To establish whether cervical length is a predictor of spontaneous preterm delivery at < or = 32 weeks in triplet pregnancies.
  
  
  METHODS
  This was a case-control study of all triplet pregnancies followed with more than three sonographic assessments of cervical length at 4-week intervals from 1995 to 2000. Cervical length in women delivered spontaneously at < or = 32 weeks (cases) was compared with that of the remaining women (controls). Statistical analysis included Fisher's exact test, chi2 test, one-way analysis of variance, logistic regression and receiver operating characteristic (ROC) curve to determine optimal cervical length thresholds for spontaneous preterm delivery at < or = 32 weeks.
  
  
  RESULTS
  Of the 58 women included in the study, 17 (29%) delivered spontaneously at < or = 32 weeks. The preterm delivery group had similar demographic and obstetric variables, but a higher rate of cerclage placement (65% vs 17%, p < 0.001) than controls. Mean +/- standard deviation cervical length was significantly shorter among cases than controls at 16-20.0 weeks (3.0 +/- 1.2 vs. 3.9 +/- 0.8 cm, p = 0.01), but not at 20.1-24.0 weeks (3.5 +/- 1.1 vs. 3.8 +/- 1.0 cm, p = 0.76). Logistic regression analysis determined that cervical length at 16-20 weeks had an odds ratio of 0.43 (95% CI = 0.23, 0.80) for the prediction of spontaneous preterm delivery at < or = 32 weeks. ROC curve analysis identified a cervical length of < or = 2.6 cm as the optimal threshold for the prediction of spontaneous preterm delivery at < or = 32 weeks (sensitivity 41%, specificity 92%).
  
  
  CONCLUSIONS
  In a population of triplet gestations with a 29% rate of preterm delivery, cervical length at 16-20.0 weeks, but not at 20.1-24.0 weeks, was inversely correlated with the probability of preterm delivery at < or = 32 weeks.
authors.affiliation: Department of Obstetrics and Gynecology, Georgetown University Hospital, Washington, District of Columbia 20007, USA.
authors.forename: S H
authors.initials: SH
authors.lastname: Poggi
authors.forename: A
authors.initials: A
authors.lastname: Ghidini
authors.forename: H J
authors.initials: HJ
authors.lastname: Landy
authors.forename: M
authors.initials: M
authors.lastname: Alvarez
authors.forename: J C
authors.initials: JC
authors.lastname: Pezzullo
authors.forename: J V
authors.initials: JV
authors.lastname: Collea
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D002584:Cervix Uteri / Q000000981:diagnostic imaging* / Q000473:pathology; D005260:Female; D005865:Gestational Age; D006801:Humans; D008499:Medical Records; D007752:Obstetric Labor, Premature / Q000175:diagnosis*; D011237:Predictive Value of Tests; D011247:Pregnancy; D011272:Pregnancy, Multiple; D012372:ROC Curve; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014310:Triplets; D016216:Ultrasonography, Prenatal / Q000379:methods / Q000592:standards*