title: Trial of labor after cesarean in the low-risk obstetric population: a retrospective nationwide cohort study.
abstract: The purpose of this study was to evaluate the risk of adverse maternal outcomes associated with trial of labor (TOL) after cesarean during subsequent pregnancies in the low-risk population.
  
  
  
  We conducted a retrospective cohort study using the Nationwide Inpatient Sample and ICD-9 diagnostic and procedure codes from the years 2003 to 2011. A cohort of low-risk pregnant women with a history of previous cesarean delivery were identified and separated into two groups: TOL and no TOL. Logistic regression analysis was used to calculate odds ratios (ORs) comparing adverse maternal outcomes between these two groups.
  
  
  
  Out of 7 290 474 registered deliveries, there were 685 137 low-risk women who met inclusion criteria. Of these women, 144 066 (21.0%) underwent a TOL, with rates remaining steady over the course of our study. The TOL group was at increased risk of overall morbidity (OR 1.74, 95% confidence interval (CI), 1.66-1.79), most notably uterine rupture (OR 22.52, 95% CI, 19.35-26.20, P<0.01). A secondary analysis showed no apparent correlation between TOL and concomitant adverse maternal outcomes in cases of uterine rupture.
  
  
  
  Although these outcomes remain rare, low-risk women undergoing a TOL remain at increased risk of adverse maternal events as compared with those who chose elective repeat cesarean delivery.
authors.affiliation: Department of Obstetrics and Gynecology, Jewish General Hospital, McGill University, Montreal, QC, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Stattmiller
authors.affiliation: Department of Obstetrics and Gynecology, Jewish General Hospital, McGill University, Montreal, QC, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Lavecchia
authors.affiliation: Center for Clinical Epidemiology and Community Studies, Jewish General Hospital, Montreal, QC, Canada.
authors.forename: N
authors.identifier: 0000-0002-2665-135X
authors.initials: N
authors.lastname: Czuzoj-Shulman
authors.affiliation: Center for Clinical Epidemiology and Community Studies, Jewish General Hospital, Montreal, QC, Canada.
authors.forename: A R
authors.initials: AR
authors.lastname: Spence
authors.affiliation: Department of Obstetrics and Gynecology, Jewish General Hospital, McGill University, Montreal, QC, Canada.|Center for Clinical Epidemiology and Community Studies, Jewish General Hospital, Montreal, QC, Canada.
authors.forename: H A
authors.initials: HA
authors.lastname: Abenhaim
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D017604:Cesarean Section, Repeat / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D016017:Odds Ratio; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology; D012044:Regression Analysis; D012189:Retrospective Studies; D014219:Trial of Labor; D016064:Vaginal Birth after Cesarean / Q000009:adverse effects* / Q000523:psychology / Q000706:statistics & numerical data; D055815:Young Adult