title: The association between the length of first stage of labor, mode of delivery, and perinatal outcomes in women undergoing induction of labor.
abstract: OBJECTIVE
  To estimate the association between the lengths of the first stage of labor, mode of delivery, and perinatal outcomes in women undergoing labor induction.
  
  
  METHODS
  Retrospective cohort study of singleton, term pregnancies with labor induction and delivered during the second stage. The length of the first stage was examined by 6-hour intervals as predictors of mode of delivery and perinatal morbidity using chi(2) test and multivariable logistic regression analysis.
  
  
  RESULTS
  There were 3620 women who met study criteria. Compared with women with a first stage between 0-12 hours, women with longer first stages had a higher risk of cesarean delivery during the second stage, up to an adjusted odds ratio of 7.44 in those with a first stage > or =24 hours (95% confidence interval [CI], 3.43-16.1). Women with a first stage > or =24 hours also had higher odds of postpartum hemorrhage (adjusted odds ratio [aOR], 3.16; 95% CI, 1.73-5.79), chorioamnionitis (aOR, 2.83; 95% CI, 1.19-6.69), and neonatal admission to the intensive care nursery (aOR, 2.03; 95% CI, 1.10-3.74).
  
  
  CONCLUSIONS
  In women who underwent induction of labor, even when a second stage of labor was reached, the risk for cesarean delivery and maternal morbidity remained increased when the length of the first stage was longer than 24 hours. However, in this clinical scenario, the frequency of cesarean delivery remains less than 50%. The decision for surgical intervention thus should not be based on the elapse of time alone.
authors.affiliation: Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California, San Francisco, CA, USA.
authors.forename: Yvonne W
authors.initials: YW
authors.lastname: Cheng
authors.forename: Shani S
authors.initials: SS
authors.lastname: Delaney
authors.forename: Linda M
authors.initials: LM
authors.lastname: Hopkins
authors.forename: Aaron B
authors.initials: AB
authors.lastname: Caughey
mesh_terms: D000328:Adult; D002585:Cesarean Section / Q000706:statistics & numerical data; D015331:Cohort Studies; D036861:Delivery, Obstetric / Q000379:methods*; D005260:Female; D006801:Humans; D007747:Labor Stage, First; D007751:Labor, Induced; D011247:Pregnancy; D011256:Pregnancy Outcome; D012189:Retrospective Studies; D013997:Time Factors