title: Prediction of Spontaneous Preterm Birth Among Nulliparous Women With a Short Cervix.
abstract: OBJECTIVE
  The purpose of this study was to evaluate whether demographic and sonographic factors associated with spontaneous preterm birth among nulliparous women with a cervical length of less than 30 mm could be combined into an accurate prediction model for spontaneous preterm birth.
  
  
  METHODS
  We conducted a secondary analysis of a trial of nulliparous women with a singleton gestation and a cervical length of less than 30 mm on transvaginal sonography between 16 and 22 weeks who lacked other risk factors for spontaneous (eg, prior cervical excisional procedure) or medically indicated (eg, chronic hypertension) preterm birth, who were randomized to either 17α-hydroxyprogesterone caproate treatment or a placebo. Risk factors associated with spontaneous preterm birth within the entire cohort were identified by univariable analysis. Factors significantly associated (P < .05) with spontaneous preterm birth were included in a multivariable logistic regression analysis to determine whether an accurate prediction model could be developed.
  
  
  RESULTS
  Of the 657 randomized patients, 109 (16.6%) had spontaneous preterm birth before 37 weeks' gestation. Logistic regression analysis revealed only cervical length (odds ratio, 1.06 per 1-mm decrease; 95% confidence interval, 1.02-1.10) to be associated with spontaneous preterm birth. The area under the receiver operating characteristic curve based on this regression was low (0.63; 95% confidence interval, 0.58-0.69). Results were similar for the outcome of spontaneous preterm birth before 34 weeks.
  
  
  CONCLUSIONS
  An accurate prediction model for spontaneous preterm birth among nulliparous women with a short cervix could not be developed.
authors.affiliation: Departments of Obstetrics and Gynecology, Northwestern University, Chicago, Illinois USA w-grobman@northwestern.edu.
authors.forename: William A
authors.initials: WA
authors.lastname: Grobman
authors.affiliation: George Washington University Biostatistics Center, Washington, DC USA.
authors.forename: Yinglei
authors.initials: Y
authors.lastname: Lai
authors.affiliation: Ohio State University, Columbus, Ohio USA.
authors.forename: Jay D
authors.initials: JD
authors.lastname: Iams
authors.affiliation: Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland USA.
authors.forename: Uma M
authors.initials: UM
authors.lastname: Reddy
authors.affiliation: Case Western Reserve University-MetroHealth Medical Center, Cleveland, Ohio USA.
authors.forename: Brian M
authors.initials: BM
authors.lastname: Mercer
authors.affiliation: University of Texas Medical Branch, Galveston, Texas USA.
authors.forename: George
authors.initials: G
authors.lastname: Saade
authors.affiliation: University of Alabama at Birmingham, Birmingham, Alabama USA.
authors.forename: Alan T
authors.initials: AT
authors.lastname: Tita
authors.affiliation: Brown University, Providence, Rhode Island USA.
authors.forename: Dwight J
authors.initials: DJ
authors.lastname: Rouse
authors.affiliation: Wayne State University, Detroit, Michigan USA.
authors.forename: Yoram
authors.initials: Y
authors.lastname: Sorokin
authors.affiliation: Columbia University, New York, New York USA.
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Wapner
authors.affiliation: University of Texas Southwestern Medical Center, Dallas, Texas USA.
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Leveno
authors.affiliation: University of Texas Health Science Center at Houston-Children's Memorial Hermann Hospital, Houston, Texas USA.
authors.forename: Sean C
authors.initials: SC
authors.lastname: Blackwell
authors.affiliation: University of Utah Health Sciences Center, Salt Lake City, Utah USA.
authors.forename: M Sean
authors.initials: MS
authors.lastname: Esplin
authors.affiliation: Oregon Health and Science University, Portland, Oregon USA.
authors.forename: Jorge E
authors.initials: JE
authors.lastname: Tolosa
authors.affiliation: University of North Carolina at Chapel Hill, Chapel Hill, North Carolina USA.
authors.forename: John M
authors.initials: JM
authors.lastname: Thorp
authors.affiliation: University of Pittsburgh, Pittsburgh, Pennsylvania USA.
authors.forename: Steve N
authors.initials: SN
authors.lastname: Caritis
mesh_terms: D000328:Adult; D001837:Body Weights and Measures / Q000379:methods*; D002584:Cervix Uteri / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D005260:Female; D006801:Humans; D011237:Predictive Value of Tests; D011247:Pregnancy; D047928:Premature Birth / Q000175:diagnosis*; D015203:Reproducibility of Results; D012307:Risk Factors; D016216:Ultrasonography, Prenatal / Q000379:methods*; D055815:Young Adult
keywords: cervical length; obstetric ultrasound; prediction; spontaneous preterm birth