title: The role of serial measurements of cervical length in asymptomatic women with triplet pregnancy.
abstract: OBJECTIVE
  To assess the predictive accuracy of serial measurements of cervical length (CL) for preterm birth in asymptomatic women with triplet pregnancy.
  
  
  METHODS
  A retrospective study of women with triplets who underwent serial sonographic measurements of CL until 28-32 weeks of gestation. The predictive accuracy of CL for preterm birth was determined at 4 periods along gestation: 18-20 weeks (period 1), 21-24 weeks (period 2), 25-27 weeks (period 3) and 28-32 weeks (period 4).
  
  
  RESULTS
  A total of 431 measurements of CL from were analyzed. CL decreased in a linear manner across gestation: 40.8 ± 7.1 mm, 36.5 ± 8.4 mm, 29.9 ± 11.4 mm and 25.0 ± 11.8 mm in periods 1, 2, 3 and 4, respectively. The difference in CL between women who did and did not deliver prematurely was small before 25 weeks (periods 1&2) but became more pronounced later in pregnancy (periods 3&4), mainly due to a rapid cervical shortening between periods 2 and 3 (shortening rate -29.0 ± 20.0% vs. -12.6 ± 20.5%, respectively, p = .01). The best predictors of preterm birth were either a single measurement of CL during period 3 or the degree of cervical shortening between periods 2 and 3.
  
  
  CONCLUSIONS
  Care providers should be aware of the limited predictive value of cervical length before 25 + 0 weeks in triplet pregnancies.
authors.affiliation: a Department of Obstetrics and Gynecology, Division of Maternal-Fetal Medicine , Sunnybrook Health Sciences Centre, University of Toronto , Ontario , Canada.
authors.forename: Hadar
authors.initials: H
authors.lastname: Rosen
authors.affiliation: b Department of Obstetrics and Gynecology , Lis Hospital for Women, Tel Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel Aviv University , Tel Aviv , Israel.
authors.forename: Liran
authors.initials: L
authors.lastname: Hiersch
authors.affiliation: a Department of Obstetrics and Gynecology, Division of Maternal-Fetal Medicine , Sunnybrook Health Sciences Centre, University of Toronto , Ontario , Canada.
authors.forename: Howie
authors.initials: H
authors.lastname: Freeman
authors.affiliation: a Department of Obstetrics and Gynecology, Division of Maternal-Fetal Medicine , Sunnybrook Health Sciences Centre, University of Toronto , Ontario , Canada.
authors.forename: Jon
authors.initials: J
authors.lastname: Barrett
authors.affiliation: a Department of Obstetrics and Gynecology, Division of Maternal-Fetal Medicine , Sunnybrook Health Sciences Centre, University of Toronto , Ontario , Canada.
authors.forename: Nir
authors.initials: N
authors.lastname: Melamed
mesh_terms: D000328:Adult; D054791:Cervical Length Measurement / Q000379:methods*; D002584:Cervix Uteri / Q000000981:diagnostic imaging*; D005260:Female; D005865:Gestational Age; D006801:Humans; D011237:Predictive Value of Tests; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D059286:Pregnancy, Triplet; D047928:Premature Birth / Q000175:diagnosis / Q000209:etiology / Q000517:prevention & control*; D012189:Retrospective Studies
keywords: Cervical length; change; prediction; preterm birth; serial; triplets