title: Gestational age at previous preterm birth does not affect cerclage efficacy.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the effect of earliest previous spontaneous preterm birth (SPTB) gestational age on cervical length, pregnancy duration, and ultrasound-indicated cerclage efficacy in a subsequent gestation.
  
  
  METHODS
  Planned secondary analysis of the National Institute of Child Health and Human Development-trial of cerclage for cervical length of <25 mm. Women with at least 1 previous SPTB between 17-33 weeks 6 days of gestation underwent serial vaginal ultrasound screening between 16 and 23 weeks 6 days of gestation; cervical length at qualifying randomization evaluation was used.
  
  
  RESULTS
  We observed a significant correlation (P = .0008) between previous SPTB gestational age and qualifying cervical length. In a linear regression model that was controlled for cervical length and cerclage, neither previous SPTB gestational age nor the interaction between cerclage and previous birth gestational age was significant predictor of subsequent birth gestational age.
  
  
  CONCLUSIONS
  Although there is an association between previous SPTB gestational age and cervical length in women with a mid-trimester cervical length of <25 mm, there does not appear to be a disproportionate benefit of cerclage in women with earlier previous SPTB.
authors.affiliation: Department of Obstetrics and Gynecology, University of California, Irvine, Irvine, CA, USA.
authors.forename: Deborah A
authors.initials: DA
authors.lastname: Wing
authors.forename: Jeff
authors.initials: J
authors.lastname: Szychowski
authors.forename: John
authors.initials: J
authors.lastname: Owen
authors.forename: Gary
authors.initials: G
authors.lastname: Hankins
authors.forename: Jay D
authors.initials: JD
authors.lastname: Iams
authors.forename: Jeanne S
authors.initials: JS
authors.lastname: Sheffield
authors.forename: Annette
authors.initials: A
authors.lastname: Perez-Delboy
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Berghella
authors.forename: Edwin R
authors.initials: ER
authors.lastname: Guzman
mesh_terms: D000328:Adult; D023802:Cerclage, Cervical; D054791:Cervical Length Measurement; D002584:Cervix Uteri / Q000000981:diagnostic imaging; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D016014:Linear Models; D011247:Pregnancy; D047928:Premature Birth / Q000517:prevention & control*; D016032:Randomized Controlled Trials as Topic