title: Is there a benefit to episiotomy at spontaneous vaginal delivery? A natural experiment.
abstract: OBJECTIVE
  Our purpose was to examine the association between maternal vaginal and perineal morbidity and episiotomy performed at spontaneous vaginal delivery.
  
  
  METHODS
  We obtained data from 17,483 consecutive spontaneous vaginal deliveries and compared the yearly rates of episiotomy, lacerations, and potential confounders with linear regression and stratified analyses.
  
  
  RESULTS
  Between 1976 and 1994 the use of episiotomy fell significantly (86.8% to 10.4%, R2 = 0.92, p = 0.0001). This change was associated with a fall in the rate of third- and fourth-degree lacerations (9.0% to 4.2%, R2 = 0.59, p = 0.0001) and a rise in the rate of intact perinea (10.3% to 26.5%, R2 = 0.68, p = 0.0001) and vaginal lacerations (5.4% to 19.3%, R2 = 0.77, p = 0.0001). These associations held in separate analyses stratified by parity and birth weight, except for the subgroup of nulliparous women with macrosomic infants.
  
  
  CONCLUSIONS
  At our institution a large reduction in the use of episiotomy in spontaneous vaginal deliveries was associated with a significant reduction in perineal trauma in all groups of women except for nulliparous women with macrosomic infants.
authors.affiliation: Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California, San Francisco, USA.
authors.forename: R K
authors.initials: RK
authors.lastname: Bansal
authors.forename: W M
authors.initials: WM
authors.lastname: Tan
authors.forename: J L
authors.initials: JL
authors.lastname: Ecker
authors.forename: J T
authors.initials: JT
authors.lastname: Bishop
authors.forename: S J
authors.initials: SJ
authors.lastname: Kilpatrick
mesh_terms: D004841:Episiotomy / Q000009:adverse effects / Q000706:statistics & numerical data; D005069:Evaluation Studies as Topic; D005260:Female; D005320:Fetal Macrosomia / Q000150:complications; D006801:Humans; D010298:Parity; D010502:Perineum / Q000293:injuries; D011247:Pregnancy; D012044:Regression Analysis; D014621:Vagina / Q000293:injuries; D014950:Wounds, Penetrating / Q000453:epidemiology / Q000209:etiology