title: Clinical and sonographic parameters at 37 weeks' gestation for predicting the risk of primary Cesarean delivery in nulliparous women.
abstract: OBJECTIVE
  To identify the clinical and sonographic parameters at 37 weeks' gestation that predict the risk of Cesarean delivery in labor for nulliparas.
  
  
  METHODS
  This prospective observational study recruited nulliparas with singleton pregnancies at 37 weeks' gestation. Determination of the Bishop score, ultrasound measurement of the cervical length, and fetal biometry were performed. The clinical parameters studied were maternal age, height and weight and Bishop score. The sonographic parameters included fetal biparietal diameter, femur length, abdominal circumference (AC), estimated fetal weight (EFW), amniotic fluid index and cervical length.
  
  
  RESULTS
  Four hundred and fifty-three women were examined; 57 women (12.6%) underwent an emergency Cesarean delivery in labor. Logistic regression analysis identified maternal age and height and fetal AC and EFW, but not cervical length or Bishop score, as the best predictors of Cesarean delivery. Of these predictors, maternal age and height and fetal AC at 37 weeks were included in a final model for risk scoring. The model was shown to have an adequate goodness of fit (P = 0.473), and the area under the receiver-operating characteristics curve was 0.758, indicating reasonably good discrimination.
  
  
  CONCLUSIONS
  Maternal age and height and fetal AC and EFW at 37 weeks' gestation are the most important parameters in predicting the risk of Cesarean delivery in nulliparas; sonographic measurement of the cervical length and the Bishop score were not predictive of Cesarean delivery. A predictive model using these parameters at 37 weeks provides useful information in the decision-making process regarding the mode of delivery.
authors.affiliation: Department of Obstetrics and Gynecology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnamsi, Korea.
authors.forename: S N
authors.initials: SN
authors.lastname: Kim
authors.forename: K H
authors.initials: KH
authors.lastname: Park
authors.forename: H J
authors.initials: HJ
authors.lastname: Jung
authors.forename: J S
authors.initials: JS
authors.lastname: Hong
authors.forename: D M
authors.initials: DM
authors.lastname: Shin
authors.forename: W S
authors.initials: WS
authors.lastname: Kang
mesh_terms: D000328:Adult; D020070:Cervical Ripening / Q000502:physiology; D002584:Cervix Uteri / Q000000981:diagnostic imaging* / Q000503:physiopathology; D002585:Cesarean Section / Q000706:statistics & numerical data*; D005260:Female; D020567:Fetal Weight / Q000502:physiology; D005865:Gestational Age; D006801:Humans; D007751:Labor, Induced; D008423:Maternal Age; D011237:Predictive Value of Tests; D011247:Pregnancy; D011446:Prospective Studies; D012372:ROC Curve; D016216:Ultrasonography, Prenatal