title: Maternal mortality and severe morbidity associated with low-risk planned cesarean delivery versus planned vaginal delivery at term.
abstract: BACKGROUND
  The rate of elective primary cesarean delivery continues to rise, owing in part to the widespread perception that the procedure is of little or no risk to healthy women.
  
  
  METHODS
  Using the Canadian Institute for Health Information's Discharge Abstract Database, we carried out a retrospective population-based cohort study of all women in Canada (excluding Quebec and Manitoba) who delivered from April 1991 through March 2005. Healthy women who underwent a primary cesarean delivery for breech presentation constituted a surrogate "planned cesarean group" considered to have undergone low-risk elective cesarean delivery, for comparison with an otherwise similar group of women who had planned to deliver vaginally.
  
  
  RESULTS
  The planned cesarean group comprised 46,766 women v. 2,292,420 in the planned vaginal delivery group; overall rates of severe morbidity for the entire 14-year period were 27.3 and 9.0, respectively, per 1000 deliveries. The planned cesarean group had increased postpartum risks of cardiac arrest (adjusted odds ratio [OR] 5.1, 95% confidence interval [CI] 4.1-6.3), wound hematoma (OR 5.1, 95% CI 4.6-5.5), hysterectomy (OR 3.2, 95% CI 2.2-4.8), major puerperal infection (OR 3.0, 95% CI 2.7-3.4), anesthetic complications (OR 2.3, 95% CI 2.0-2.6), venous thromboembolism (OR 2.2, 95% CI 1.5-3.2) and hemorrhage requiring hysterectomy (OR 2.1, 95% CI 1.2-3.8), and stayed in hospital longer (adjusted mean difference 1.47 d, 95% CI 1.46-1.49 d) than those in the planned vaginal delivery group, but a lower risk of hemorrhage requiring blood transfusion (OR 0.4, 95% CI 0.2-0.8). Absolute risk increases in severe maternal morbidity rates were low (e.g., for postpartum cardiac arrest, the increase with planned cesarean delivery was 1.6 per 1000 deliveries, 95% CI 1.2-2.1). The difference in the rate of in-hospital maternal death between the 2 groups was nonsignificant (p = 0.87).
  
  
  CONCLUSIONS
  Although the absolute difference is small, the risks of severe maternal morbidity associated with planned cesarean delivery are higher than those associated with planned vaginal delivery. These risks should be considered by women contemplating an elective cesarean delivery and by their physicians.
authors.affiliation: Health Surveillance and Epidemiology Division, Centre for Health Promotion, Public Health Agency of Canada, Ottawa, Ont. Shiliang_Liu@phac-aspc.gc.ca
authors.forename: Shiliang
authors.initials: S
authors.lastname: Liu
authors.forename: Robert M
authors.initials: RM
authors.lastname: Liston
authors.forename: K S
authors.initials: KS
authors.lastname: Joseph
authors.forename: Maureen
authors.initials: M
authors.lastname: Heaman
authors.forename: Reg
authors.initials: R
authors.lastname: Sauve
authors.forename: Michael S
authors.initials: MS
authors.lastname: Kramer
mesh_terms: D000328:Adult; D001946:Breech Presentation; D002170:Canada / Q000453:epidemiology; D016022:Case-Control Studies; D002585:Cesarean Section / Q000401:mortality* / Q000706:statistics & numerical data; D036861:Delivery, Obstetric / Q000592:standards / Q000639:trends; D017558:Elective Surgical Procedures / Q000592:standards* / Q000639:trends; D005260:Female; D006302:Health Services Research; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D008423:Maternal Age; D008428:Maternal Mortality / Q000639:trends*; D009017:Morbidity; D009321:Natural Childbirth; D007744:Obstetric Labor Complications / Q000401:mortality; D010347:Patient Care Planning / Q000592:standards* / Q000639:trends; D011247:Pregnancy; D011336:Probability; D012016:Reference Values; D018570:Risk Assessment; D016019:Survival Analysis; D047929:Term Birth