title: Associated factors and outcomes of persistent occiput posterior position: A retrospective cohort study from 1976 to 2001.
abstract: OBJECTIVE
  To identify maternal and fetal risk factors associated with persistent occiput posterior position at delivery, and to examine the association of occiput posterior position with subsequent obstetric outcomes.
  
  
  METHODS
  This is a retrospective cohort study of 30 839 term, cephalic, singleton births. Women with persistent occiput posterior (OP) position at delivery were compared to those with occiput anterior (OA) position. Demographics, obstetric history, and labor management were evaluated and subsequent obstetric outcomes examined. Potential confounding variables were controlled for using multivariate logistic regression analysis.
  
  
  RESULTS
  The overall frequency of OP position was 8.3% in the study population. When compared to Caucasians, a higher rate of OP was observed among African-Americans (OR = 1.4, 95% CI 1.25-1.64) while no other racial/ethnic differences were noted. Other associated factors included nulliparity, maternal age > or =35, gestational age > or =41 weeks, and birth weight >4000 g, as well as artificial rupture of the membranes (AROM) and epidural anesthesia (p < 0.001 for all). Persistent OP was associated with increased rates of operative vaginal (OR = 4.14, 95% CI 3.57-4.81) and cesarean deliveries (OR = 13.45, 95% CI 11.94-15.15) and other peripartum complications including third or fourth degree perineal lacerations (OR = 2.38, 95% CI 2.03-2.79), and chorioamnionitis (OR = 2.10, 95% CI 1.81-2.44).
  
  
  CONCLUSIONS
  Epidural use, AROM, African-American ethnicity, nulliparity, and birth weight >4000 g are associated with persistent OP position at delivery, with higher rates of operative deliveries and obstetric complications. This information can be useful in counseling patients regarding risks and associated outcomes of persistent OP position.
authors.affiliation: Division of Maternal-Fetal Medicine, Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco, CA 94143, USA. yvecheng@hotmail.com
authors.forename: Yvonne W
authors.initials: YW
authors.lastname: Cheng
authors.forename: Brian L
authors.initials: BL
authors.lastname: Shaffer
authors.forename: Aaron B
authors.initials: AB
authors.lastname: Caughey
mesh_terms: D000328:Adult; D000767:Anesthesia, Epidural; D001724:Birth Weight; D015331:Cohort Studies; D036861:Delivery, Obstetric; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D007746:Labor Presentation; D007751:Labor, Induced; D010298:Parity; D011247:Pregnancy; D011256:Pregnancy Outcome; D012189:Retrospective Studies; D012307:Risk Factors; D012959:Socioeconomic Factors