title: A model to predict vaginal delivery in nulliparous women based on maternal characteristics and intrapartum ultrasound.
abstract: OBJECTIVE
  Accurate prediction of whether a nulliparous woman will have a vaginal delivery would be a major advance in obstetrics. The objective of the study was to develop such a model based on maternal characteristics and the results of intrapartum ultrasound.
  
  
  METHODS
  One hundred twenty-two nulliparous women in the first stage of labor were included in a prospective observational 2-centre study. Labor was classified as prolonged according to the respective countries' national guidelines. Fetal head position was assessed with transabdominal ultrasound and cervical dilatation by digital examination, and transperineal ultrasound was used to determine head-perineum distance and the presence of caput succedaneum. The subjects were divided into a testing set (n = 61) and a validation set (n = 61) and a risk score derived using multivariable logistic regression with vaginal birth as the outcome, which was dichotomized into no/cesarean delivery and yes/vaginal birth. Covariates included head-perineum distance, caput succedaneum, and occiput posterior position, which were dichotomized respectively into the following: ≤40 mm, >40 mm, <10 mm, ≥10 mm, and no, yes. Maternal age, gestational age, and maternal body mass index were included as continuous covariates.
  
  
  RESULTS
  Dichotomized score is significantly associated with vaginal delivery (P = .03). Women with a score above the median had greater than 10 times the odds of having a vaginal delivery as compared with those with a score below the median. The receiver-operating characteristic curve showed an area under the curve of 0.853 (95% confidence interval, 0.678-1.000).
  
  
  CONCLUSIONS
  A risk score based on maternal characteristics and intrapartum findings can predict vaginal delivery in nulliparous women in the first stage of labor.
authors.affiliation: Department of Obstetrics and Gynecology, Stavanger University Hospital, Stavanger, Norway; National Center for Fetal Medicine, Trondheim University Hospital (St Olav's Hospital), Trondheim, Norway.
authors.forename: Tørbjorn Moe
authors.initials: TM
authors.lastname: Eggebø
authors.affiliation: ICTU-Cancer Clinical Trials Unit, Department of Surgery and Cancer, Imperial College London, London, United Kingdom.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Wilhelm-Benartzi
authors.affiliation: Department of Fetal Medicine, Rosie Maternity Hospital, Addenbrooke's Hospital, Cambridge University Hospitals National Health Service Foundation Trust, Cambridge, United Kingdom.
authors.forename: Wassim A
authors.initials: WA
authors.lastname: Hassan
authors.affiliation: Department of Cancer and Surgery, Imperial College London, Centre for Fetal Care, Queen Charlotte's and Chelsea Hospital, Imperial College Healthcare National Health Service Trust, London, United Kingdom.
authors.forename: Sana
authors.initials: S
authors.lastname: Usman
authors.affiliation: Department of Laboratory Medicine, Children's and Women's Health, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Kjell A
authors.initials: KA
authors.lastname: Salvesen
authors.affiliation: Department of Cancer and Surgery, Imperial College London, Centre for Fetal Care, Queen Charlotte's and Chelsea Hospital, Imperial College Healthcare National Health Service Trust, London, United Kingdom; Department of Development and Regeneration, KU Leuven, Belgium. Electronic address: christoph.lees@imperial.nhs.uk.
authors.forename: Christoph C
authors.initials: CC
authors.lastname: Lees
mesh_terms: D000328:Adult; D015992:Body Mass Index; D015331:Cohort Studies; D003661:Decision Support Techniques; D036861:Delivery, Obstetric / Q000706:statistics & numerical data*; D004420:Dystocia / Q000000981:diagnostic imaging / Q000453:epidemiology*; D005260:Female; D005865:Gestational Age; D006801:Humans; D007746:Labor Presentation; D007743:Labor, Obstetric; D016015:Logistic Models; D008423:Maternal Age; D010298:Parity; D010502:Perineum / Q000000981:diagnostic imaging*; D011247:Pregnancy; D011446:Prospective Studies; D016216:Ultrasonography, Prenatal; D055815:Young Adult
keywords: cesarean delivery; head-perineum distance; prediction model; transperineal