title: Is there a role for cervical assessment and uterine artery Doppler in the first trimester of pregnancy as a screening test for spontaneous preterm delivery?
abstract: OBJECTIVE
  To evaluate the role of cervical length (CL) and uterine artery pulsatility index (UtA-PI) at 11+0 to 13+6 weeks as predictors of spontaneous preterm delivery (sPTD) in a Chilean population.
  
  
  METHODS
  This was a prospective study of asymptomatic women with singleton pregnancies attending for a nuchal translucency scan at 11+0 to 13+6 weeks' gestation and who underwent a transvaginal scan for evaluation of CL and UtA-PI. Exclusion criteria were fetal and pregnancy complications (other than sPTD) and iatrogenic delivery at<34 weeks. Measurements of CL and UtA-PI were adjusted for fetal crown-rump length and maternal characteristics and expressed as multiples of the median (MoM) of the unaffected group. Prediction of sPTD using maternal and pregnancy characteristics was studied using logistic regression analysis.
  
  
  RESULTS
  A total of 3480 women were recruited into the study and, after application of exclusion criteria, 3310 were included in the analysis. The rate of sPTD at<34 weeks was 0.9% (n=31). A previous PTD had occurred in 7.4% of parous women. Patients with sPTD in the index pregnancy were characterized by a significantly higher prevalence of previous PTD (12.9% vs 3.7%, P<0.05). No significant difference was found in either CL or UtA-PI between pregnancies with and without subsequent sPTD. Logistic regression analysis showed that smoking and previous PTD were significantly associated with sPTD at<34 weeks. The combination of these characteristics provided a detection rate of 26% with a false-positive rate of 8%.
  
  
  CONCLUSIONS
  Neither UtA-PI nor CL during the first trimester was shown to be a useful predictor of early sPTD. However, a combined model that includes smoking and previous PTD predicts approximately one-quarter of those women destined to deliver at<34 weeks, with a false-positive rate of 8%.
authors.affiliation: Fetal Medicine Unit, University of Chile Hospital, Santiago, Chile; Fetal Medicine Unit, Hospital San Borja Arriarán, Santiago, Chile.
authors.forename: M
authors.initials: M
authors.lastname: Parra-Cordero
authors.forename: A
authors.initials: A
authors.lastname: Sepúlveda-Martínez
authors.forename: G
authors.initials: G
authors.lastname: Rencoret
authors.forename: E
authors.initials: E
authors.lastname: Valdés
authors.forename: D
authors.initials: D
authors.lastname: Pedraza
authors.forename: H
authors.initials: H
authors.lastname: Muñoz
mesh_terms: D000328:Adult; D002584:Cervix Uteri / Q000000981:diagnostic imaging* / Q000473:pathology; D018568:Crown-Rump Length; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D048208:Nuchal Translucency Measurement; D007752:Obstetric Labor, Premature / Q000000981:diagnostic imaging*; D010927:Placental Insufficiency / Q000000981:diagnostic imaging* / Q000473:pathology; D011237:Predictive Value of Tests; D011247:Pregnancy; D011248:Pregnancy Complications / Q000000981:diagnostic imaging*; D011261:Pregnancy Trimester, First; D047928:Premature Birth; D011446:Prospective Studies; D011673:Pulsatile Flow; D012372:ROC Curve; D012680:Sensitivity and Specificity; D055988:Uterine Artery / Q000000981:diagnostic imaging*; D014599:Uterus / Q000000981:diagnostic imaging*
keywords: cervical length; first-trimester screening; preterm delivery; uterine artery Doppler