title: Ultrasound assessment of fetal head circumference at the onset of labor as a predictor of operative delivery.
abstract: OBJECTIVE
  This study sought to determine whether ultrasound assessment of fetal head circumference (FHC) at the onset of labor can predict the likelihood of operative delivery.
  
  
  METHODS
  We performed a prospective cohort study of 200 nulliparous women with singleton, cephalic, term pregnancies in an Irish Maternity Hospital. Transabdominal ultrasound assessment of FHC was performed when spontaneous labor was diagnosed or immediately prior to induction. Odds ratios for operative delivery (instrumental delivery or cesarean section) and maternal and neonatal morbidity were calculated using logistic regression with FHC categorized at a ≥350-mm cut-off (90th percentile).
  
  
  RESULTS
  Ultrasound assessment of FHC at the onset of labor was highly correlated with post-delivery neonatal head circumference (NHC) (Pearson's correlation coefficient 0.74), suggesting that it can be measured reliably. FHC ≥350 mm was associated with more than twice the risk of any operative delivery (OR 2.5, 95% CI 1.0-6.2) and a two-fold increased risk of cesarean section for dystocia (OR 2.0, 95% CI 1.0-4.3). Differences in maternal and neonatal morbidity were not statistically significant.
  
  
  CONCLUSIONS
  These preliminary data suggest that ultrasound assessment of FHC at the onset of labor may be useful in identifying women at greater risk of intrapartum intervention and warrant further research.
authors.affiliation: a University Maternity Hospital , Limerick , Republic of Ireland .|b Department of Obstetrics and Gynaecology , Trinity College , Dublin , Republic of Ireland .
authors.forename: Poh Vei
authors.initials: PV
authors.lastname: Ooi
authors.affiliation: b Department of Obstetrics and Gynaecology , Trinity College , Dublin , Republic of Ireland .|c Coombe Women and Infants University Hospital , Dublin , Republic of Ireland , and.
authors.forename: Meenakshi
authors.initials: M
authors.lastname: Ramphul
authors.affiliation: a University Maternity Hospital , Limerick , Republic of Ireland .|d Department of Obstetrics and Gynaecology , Graduate Entry Medical School, University of Limerick , Limerick , Republic of Ireland.
authors.forename: Soha
authors.initials: S
authors.lastname: Said
authors.affiliation: a University Maternity Hospital , Limerick , Republic of Ireland .|d Department of Obstetrics and Gynaecology , Graduate Entry Medical School, University of Limerick , Limerick , Republic of Ireland.
authors.forename: Gerard
authors.initials: G
authors.lastname: Burke
authors.affiliation: b Department of Obstetrics and Gynaecology , Trinity College , Dublin , Republic of Ireland .
authors.forename: Mairead M
authors.initials: MM
authors.lastname: Kennelly
authors.affiliation: b Department of Obstetrics and Gynaecology , Trinity College , Dublin , Republic of Ireland .|c Coombe Women and Infants University Hospital , Dublin , Republic of Ireland , and.
authors.forename: Deirdre J
authors.initials: DJ
authors.lastname: Murphy
mesh_terms: D000328:Adult; D002508:Cephalometry; D002585:Cesarean Section; D005113:Extraction, Obstetrical; D005260:Female; D005333:Fetus; D006257:Head / Q000000981:diagnostic imaging* / Q000196:embryology; D006801:Humans; D007745:Labor Onset; D016017:Odds Ratio; D011237:Predictive Value of Tests; D011247:Pregnancy; D011446:Prospective Studies; D012372:ROC Curve; D012307:Risk Factors; D016216:Ultrasonography, Prenatal
keywords: Cesarean section; fetal head circumference; instrumental delivery; labor; ultrasound