title: Cervical-length measurement in mid-gestation to predict spontaneous preterm birth in asymptomatic triplet pregnancy.
abstract: OBJECTIVE
  To assess the predictive value of sonographic cervical-length (CL) measurement in mid-gestation for spontaneous preterm birth (PTB) in asymptomatic triplet pregnancy.
  
  
  METHODS
  This was a retrospective study of asymptomatic triplet pregnancies followed at five Italian tertiary referral centers, between 2002 and 2015. CL was measured transvaginally between 18 and 24 weeks' gestation. Pregnancies with medically indicated PTB were excluded. Demographic and pregnancy characteristics of pregnancies complicated by PTB were analyzed and the distributions of CL measurements in these patients were calculated. Logistic regression analysis was performed to assess the association between CL and PTB, adjusted for confounders. Performance of CL measurement in prediction of PTB < 28, < 30 and < 32 weeks of gestation was assessed.
  
  
  RESULTS
  A total of 120 triplet pregnancies were included in the final analysis. Median CL was 35 (interquartile range (IQR), 29-40) mm measured at a median gestational age of 20 + 2 (IQR, 20 + 0 to 23 + 4) weeks. Overall, 23 (19.2%), 17 (14.2%) and eight (6.7%) patients had a CL < 25, < 20 and < 15 mm, respectively. Spontaneous PTB < 32 weeks occurred in 41 (34.2%) cases, < 30 weeks in 23 (19.2%) and < 28 weeks in 12 (10%) cases. CL < 15 mm was significantly more frequent in the group of patients who delivered < 28 (P = 0.03) and < 30 (P = 0.01) weeks' gestation, compared with those who delivered after 28 and after 30 weeks, respectively, while CL < 20 mm was more common in triplet pregnancies with delivery < 32 weeks compared with those delivered ≥ 32 weeks (P = 0.03). Logistic regression analysis was possible only for PTB < 32 weeks due to the small number of cases that delivered < 30 and < 28 weeks. After adjustment for confounders, CL was not significantly associated with PTB < 32 weeks (adjusted odds ratio, 0.97; 95% CI, 0.94-1.01). CL measurement had an area under the receiver-operating characteristics curve of 0.41 (95% CI, 0.20-0.62), 0.41 (95% CI, 0.26-0.56) and 0.42 (95% CI, 0.31-0.54) for the prediction of spontaneous PTB < 28, < 30 and < 32 weeks, respectively.
  
  
  CONCLUSIONS
  CL assessed in mid-gestation is a poor predictor of PTB < 28, < 30 and < 32 weeks' gestation in asymptomatic triplet pregnancy. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.
authors.affiliation: Department of Obstetrics and Gynaecology, University of Brescia, Brescia, Italy.
authors.forename: A
authors.identifier: http://orcid.org/0000-0002-7368-0823
authors.initials: A
authors.lastname: Fichera
authors.affiliation: Department of Obstetrics and Gynaecology, University of Brescia, Brescia, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Pagani
authors.affiliation: Department of Obstetrics and Gynaecology, University of Brescia, Brescia, Italy.
authors.forename: V
authors.initials: V
authors.lastname: Stagnati
authors.affiliation: Department of Obstetrics and Gynaecology, University of Verona, Verona, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Cascella
authors.affiliation: Children's Hospital V. Buzzi, Milan, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Faiola
authors.affiliation: Department for Woman and Child Health, AOU Careggi, Florence, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Gaini
authors.affiliation: Children's Hospital V. Buzzi, Milan, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Lanna
authors.affiliation: Department for Woman and Child Health, AOU Careggi, Florence, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Pasquini
authors.affiliation: Department of Obstetrics and Gynaecology, University of Verona, Verona, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Raffaelli
authors.affiliation: Unit of Prenatal Diagnosis, Institute for Maternal and Child Health, IRCCS Burlo Garofolo, Trieste, Italy.
authors.forename: T
authors.initials: T
authors.lastname: Stampalija
authors.affiliation: Unit of Prenatal Diagnosis, Institute for Maternal and Child Health, IRCCS Burlo Garofolo, Trieste, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Tommasini
authors.affiliation: Department of Obstetrics and Gynaecology, University of Brescia, Brescia, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Prefumo
mesh_terms: D000328:Adult; D054791:Cervical Length Measurement; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D016015:Logistic Models; D011237:Predictive Value of Tests; D011247:Pregnancy; D059286:Pregnancy, Triplet; D047928:Premature Birth / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology; D012189:Retrospective Studies
keywords: multiple pregnancy; predictive test; preterm birth; triplets; ultrasound cervical length