title: Can shoulder dystocia be reliably predicted?
abstract: OBJECTIVE
  To evaluate factors reported to increase the risk of shoulder dystocia, and to evaluate their predictive value at a population level.
  
  
  METHODS
  The South Australian Pregnancy Outcome Unit's population database from 2005 to 2010 was accessed to determine the occurrence of shoulder dystocia in addition to reported risk factors, including age, parity, self-reported ethnicity, presence of diabetes and infant birth weight. Odds ratios (and 95% confidence interval) of shoulder dystocia was calculated for each risk factor, which were then incorporated into a logistic regression model. Test characteristics for each variable in predicting shoulder dystocia were calculated.
  
  
  RESULTS
  As a proportion of all births, the reported rate of shoulder dystocia increased significantly from 0.95% in 2005 to 1.38% in 2010 (P = 0.0002). Using a logistic regression model, induction of labour and infant birth weight greater than both 4000 and 4500 g were identified as significant independent predictors of shoulder dystocia. The value of risk factors alone and when incorporated into the logistic regression model was poorly predictive of the occurrence of shoulder dystocia.
  
  
  CONCLUSIONS
  While there are a number of factors associated with an increased risk of shoulder dystocia, none are of sufficient sensitivity or positive predictive value to allow their use clinically to reliably and accurately identify the occurrence of shoulder dystocia.
authors.affiliation: Discipline of Obstetrics and Gynaecology, Robinson Institute, The University of Adelaide, 72 King William Road, North Adelaide, SA 5006, Australia. jodie.dodd@adelaide.edu.au
authors.forename: Jodie M
authors.initials: JM
authors.lastname: Dodd
authors.forename: Britt
authors.initials: B
authors.lastname: Catcheside
authors.forename: Wendy
authors.initials: W
authors.lastname: Scheil
mesh_terms: D000328:Adult; D001724:Birth Weight; D004420:Dystocia / Q000175:diagnosis / Q000453:epidemiology*; D005260:Female; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D011237:Predictive Value of Tests; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000453:epidemiology; D012306:Risk; D012782:Shoulder; D013021:South Australia / Q000453:epidemiology