title: [Epidemiology of shoulder dystocia].
abstract: OBJECTIVE
  To synthetize the available evidence regarding the incidence and risk factors of shoulder dystocia (SD).
  
  
  METHODS
  Consultation of the Medline database, and of national guidelines.
  
  
  RESULTS
  Shoulder dystocia is defined as a vaginal delivery that requires additional obstetric manoeuvres to deliver the foetus after the head has delivered and gentle traction has failed. With this definition, the incidence of SD in population-based studies is about 0.5-1% of vaginal deliveries. Many risk factors have been described but most associations are not independent, or have not been constantly found. The 2 characteristics consistently found as independent risk factors for SD in the literature are previous SD (incidence of SD of about 10% in parturients with previous SD) and foetal macrosomia. Maternal diabetes and obesity also are associated with a higher risk of SD (2 to 4 folds) but these associations may be completely explained by foetal macrosomia. However, even factors independently and constantly associated with SD do not allow a valid prediction of SD because they are not discriminant; 50 to 70% of SD cases occur in their absence, and the great majority of deliveries when they are present is not associated with SD.
  
  
  CONCLUSIONS
  Shoulder dystocia is defined by the need for additional obstetric manoeuvres to deliver the foetus after the head has delivered and gentle traction has failed, and complicates 0.5-1% of vaginal deliveries. Its main risk factors are previous SD and macrosomia, but they are poorly predictive. SD remains a non-predictable obstetrics emergency. Knowledge of SD risk factors should increase the vigilance of clinicians in at-risk contexts.
authors.affiliation: Inserm U1153, épidémiologie obstétricale, périnatale et pédiatrique (équipe EPOPé), centre de recherche en épidémiologie et statistiques Sorbonne Paris Cité (CRESS), DHU risques et grossesse, université Paris Descartes, maternité Port-Royal, 6(e) étage, 53, avenue de l'Observatoire, 75014 Paris, France. Electronic address: catherine.deneux-tharaux@inserm.fr.
authors.forename: C
authors.initials: C
authors.lastname: Deneux-Tharaux
authors.affiliation: Service de gynécologie-obstétrique, groupe hospitalier Saint-Joseph, 75014 Paris, France.
authors.forename: P
authors.initials: P
authors.lastname: Delorme
mesh_terms: D001720:Birth Injuries / Q000453:epidemiology*; D036861:Delivery, Obstetric / Q000009:adverse effects / Q000706:statistics & numerical data*; D004420:Dystocia / Q000453:epidemiology* / Q000628:therapy; D005260:Female; D005320:Fetal Macrosomia / Q000150:complications / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D011247:Pregnancy; D012307:Risk Factors; D012782:Shoulder
keywords: Definition; Dystocie des épaules; Définition; Epidemiology; Facteurs de risque; Incidence; Risk factors; Shoulder dystocia; Épidémiologie