title: Elevated amniotic fluid lactate predicts labor disorders and cesarean delivery in nulliparous women at term.
abstract: OBJECTIVE
  We sought to assess amniotic fluid lactate (AFL) at diagnosis of spontaneous labor at term (≥37 weeks) as a predictor of labor disorders (dystocia) and cesarean delivery (CD).
  
  
  METHODS
  This was a single-institution, prospective cohort study of 905 singleton, cephalic, term (≥37 weeks) nulliparous women in spontaneous labor. A standard management of labor (active management of labor) including a standard oxytocin regimen up to a maximum dose of 30 mU/min was applied. AFL was measured using a point-of-care device (LMU061; ObsteCare, Stockholm, Sweden). Labor arrest in the first stage of labor was defined as the need for oxytocin when cervical dilatation was <1 cm/h over 2 hours and in the second stage of labor by poor descent and rotation over 1 hour. Standard statistical analysis included analysis of variance, Pearson correlations, and binary logistic regression. Unsupervised decision tree analysis with 10-fold cross-validation was used to identify AFL thresholds.
  
  
  RESULTS
  AFL was normally distributed and did not correlate with age, body mass index, or gestation. Unsupervised decision tree analysis demonstrated that AFL could be divided into 3 groups: 0-4.9 mmol/L (n = 118), 5.0-9.9 mmol/L (n = 707), and ≥10.0 mmol/L (n = 80). Increasing AFL was associated with higher total oxytocin dose (P = .001), labor disorders (P = .005), and CD (P ≤ .001). Multivariable regression analysis demonstrated that women with AFL ≥5.0-9.9 mmol/L (odds ratio [OR], 1.6; 95% confidence interval [CI], 1.06-2.39) and AFL ≥10.0 mmol/L (OR, 1.72; 95% CI, 1.01-2.93) were independent predictors of a labor disorder. AFL ≥5.0-9.9 mmol/L did not predict CD but multivariable analysis confirmed that AFL ≥10.0 mmol/L was an independent predictor of CD (OR, 3.35; 95% CI, 1.73-6.46). AFL ≥5.0-9.9 mmol/L had a sensitivity of 89% in predicting a labor disorder and a sensitivity of 93% in predicting CD with a 97% negative predictive value. AFL ≥10.0 mmol/L was highly specific but lacked sensitivity for CD. There was no difference in birthweight of infants according to labor disorder and delivery method.
  
  
  CONCLUSIONS
  AFL at diagnosis of labor in spontaneously laboring single cephalic nulliparous term women is an independent predictor of a labor disorder and CD. These data suggest that women with AFL between 5.0-9.9 mmol/L with a labor disorder may be amenable to correction using the active management of labor protocol.
authors.affiliation: Department of Midwifery, National Maternity Hospital, Dublin, Ireland; Department of Health Sciences, University College Dublin, Dublin, Ireland. Electronic address: tinamurphy@nmh.ie.
authors.forename: Martina
authors.initials: M
authors.lastname: Murphy
authors.affiliation: School of Midwifery, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Michelle
authors.initials: M
authors.lastname: Butler
authors.affiliation: Department of Health Sciences, University College Dublin, Dublin, Ireland.
authors.forename: Barbara
authors.initials: B
authors.lastname: Coughlan
authors.affiliation: Department of Obstetrics and Gynecology, National Maternity Hospital, Dublin, Ireland; Department of Obstetrics and Gynecology, University College Dublin, Dublin, Ireland.
authors.forename: Donal
authors.initials: D
authors.lastname: Brennan
authors.affiliation: Department of Obstetrics and Gynecology, National Maternity Hospital, Dublin, Ireland; Department of Obstetrics and Gynecology, University College Dublin, Dublin, Ireland.
authors.forename: Colm
authors.initials: C
authors.lastname: O'Herlihy
authors.affiliation: Department of Obstetrics and Gynecology, National Maternity Hospital, Dublin, Ireland.
authors.forename: Michael
authors.initials: M
authors.lastname: Robson
mesh_terms: D000293:Adolescent; D000328:Adult; D000653:Amniotic Fluid / Q000737:chemistry*; D002585:Cesarean Section; D003663:Decision Trees; D004420:Dystocia / Q000175:diagnosis* / Q000378:metabolism* / Q000503:physiopathology; D005260:Female; D006801:Humans; D015999:Multivariate Analysis; D007744:Obstetric Labor Complications / Q000175:diagnosis* / Q000378:metabolism; D011237:Predictive Value of Tests; D011247:Pregnancy; D011446:Prospective Studies; D014599:Uterus / Q000503:physiopathology; D055815:Young Adult
keywords: active management of labor; amniotic fluid lactate; cesarean delivery; labor disorder (dystocia)