title: Risk of shoulder dystocia in second delivery: does a history of shoulder dystocia matter?
abstract: OBJECTIVE
  Our aim was to estimate the relative and absolute risk of shoulder dystocia in the second delivery according to history of shoulder dystocia and offspring birthweight.
  
  
  METHODS
  A retrospective cohort study including all women in Norway with 2 consecutive singleton vaginal deliveries with fetus in cephalic presentation, during the period 1967-2005 (n = 537,316).
  
  
  RESULTS
  In the second delivery shoulder dystocia occurred in 0.8% of all women. In women with a prior shoulder dystocia the recurrence risk was 7.3%. Most cases of shoulder dystocia in second delivery were in women without such history (96.2%). Offspring birthweight was the most important risk factor for shoulder dystocia in second delivery: crude odds ratio, 292.9 (95% confidence interval, 237.8-360.7) comparing birthweight > 5000 g with 3000-3499 g.
  
  
  CONCLUSIONS
  Prior shoulder dystocia increased the risk of shoulder dystocia in the second delivery. However, offspring birthweight was by far the most important risk factor.
authors.affiliation: Department of Obstetrics and Gynecology and Medical Faculty Division, Akershus University Hospital, University of Oslo, Oslo, Norway.
authors.forename: Eva A
authors.initials: EA
authors.lastname: Overland
authors.forename: Anny
authors.initials: A
authors.lastname: Spydslaug
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Nielsen
authors.forename: Anne
authors.initials: A
authors.lastname: Eskild
mesh_terms: D000328:Adult; D001720:Birth Injuries / Q000453:epidemiology*; D001724:Birth Weight; D004420:Dystocia / Q000453:epidemiology*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007746:Labor Presentation; D009664:Norway / Q000453:epidemiology; D010298:Parity; D011247:Pregnancy; D012008:Recurrence; D012042:Registries; D012189:Retrospective Studies; D012307:Risk Factors; D012782:Shoulder; D055815:Young Adult