title: High birthweight and shoulder dystocia: the strongest risk factors for obstetrical brachial plexus palsy in a Swedish population-based study.
abstract: BACKGROUND
  Obstetrical brachial plexus palsy (OBPP) is a serious form of neonatal morbidity.
  
  
  OBJECTIVE
  The aim of this work was to study the incidence of OBPP and to analyze its risk factors.
  
  
  METHODS
  This is a population-based retrospective case-control study. All deliveries recorded in the Swedish Medical Birth Registry between 1987 and 1997 (n = 1 213 987) were investigated. Cases (n = 2399) with OBPP were compared to all other cases.
  
  
  RESULTS
  The incidence of OBPP increased from 0.17 in 1987 to 0.27% in 1997 (p = 0.002). During the same time period, the mean birthweight increased from 3483 to 3525 g. Birthweight increasing from 4000 g was associated with a progressive rise in OBPP risk. Other significant risk factors associated with the injury were shoulder dystocia, breech presentation in vaginal delivery, operative vaginal delivery, diabetes mellitus, induction of labor, protracted active phase, secondary arrest of dilatation, and epidural anesthesia. Cesarean section was associated with a decreased risk of OBPP. If 5000 g is chosen as cut-off for cesarean section, 85% of the infants in this weight class are underestimated using ultrasonography. Approximately, 331 abdominal deliveries have to be performed to avoid one case of OBPP.
  
  
  CONCLUSIONS
  Shoulder dystocia and infant birthweight of 4500 g and more are the strongest risk factors for OBPP in a Swedish population.
authors.affiliation: Department of Obstetrics and Gynecology, Sahlgrenska University Hospital, University of Göteborg, Sweden. margareta.mollberg@vgregion.se
authors.forename: Margareta
authors.initials: M
authors.lastname: Mollberg
authors.forename: Henrik
authors.initials: H
authors.lastname: Hagberg
authors.forename: Börje
authors.initials: B
authors.lastname: Bager
authors.forename: Håkan
authors.initials: H
authors.lastname: Lilja
authors.forename: Lars
authors.initials: L
authors.lastname: Ladfors
mesh_terms: D001720:Birth Injuries / Q000453:epidemiology / Q000209:etiology*; D001724:Birth Weight; D020516:Brachial Plexus Neuropathies / Q000453:epidemiology / Q000209:etiology*; D036861:Delivery, Obstetric; D004420:Dystocia / Q000453:epidemiology / Q000209:etiology*; D005260:Female; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D016015:Logistic Models; D011247:Pregnancy; D015995:Prevalence; D012042:Registries; D012307:Risk Factors; D013548:Sweden / Q000453:epidemiology