title: Factors contributing to the increased cesarean birth rate in older parturient women.
abstract: OBJECTIVE
  Our purpose was to determine factors contributing to the increased use of cesarean section in patients > or = 35 years old.
  
  
  METHODS
  Data were collected prospectively on nulliparous patients in spontaneous labor with term, singleton pregnancies and vertex presentations. Criteria for the diagnosis of labor were standardized: regular, painful uterine contractions at least once every 5 minutes in the presence of either complete cervical effacement or spontaneous rupture of membranes. The labors of women > or = 35 years old (n = 74) were compared with those of women 20 to 29 years old (n = 275).
  
  
  RESULTS
  The cesarean section rate was significantly greater for patients > or = 35 years old (21.6% vs 10.2%, odds ratio 2.4, 95% confidence interval 1.2 to 5.1). Mean birth weights were similar in the two groups, but when birth weight was > or = 3600 gm patients > or = 35 years old were more likely to be delivered by cesarean section (36.7% vs 12.2%, odds ratio 4.0, 95% confidence interval 1.4 to 11.9). There were no differences between the two age groups in physician factors that could explain the disparate rates of cesarean delivery. Indeed, of patients delivered vaginally the older parturients received oxytocin for longer duration (6.4 +/- 2.6 vs 5.0 +/- 3.1 hours, p < 0.05) and at higher maximum doses (12.4 +/- 6.1 vs 9.8 +/- 6.2 mU, p < 0.05). After controlling for potentially confounding variables with multiple logistic regression analysis, maternal age (R = 0.125, p < 0.005), birth weight (R = 0.196, p < 0.001), the need for oxytocin (R = 0.210, p < 0.001), and epidural anesthesia (R = 0.195, p < 0.001) were found to be independently associated with the increased rate of cesarean section.
  
  
  CONCLUSIONS
  We could not identify any controllable physician factors affecting the rate of cesarean section in patients > or = 35 years old. The increased oxytocin requirements and the incidence of dystocia with birth weight > or = 3600 gm suggest that maternal and fetal characteristics contribute to the increased frequency of cesarean section in older parturients.
authors.affiliation: Department of Obstetrics and Gynecology, Northwestern University Medical School, Chicago, Illinois.
authors.forename: J A
authors.initials: JA
authors.lastname: Adashek
authors.forename: A M
authors.initials: AM
authors.lastname: Peaceman
authors.forename: J A
authors.initials: JA
authors.lastname: Lopez-Zeno
authors.forename: J P
authors.initials: JP
authors.lastname: Minogue
authors.forename: M L
authors.initials: ML
authors.lastname: Socol
mesh_terms: D000328:Adult; D001724:Birth Weight; D002585:Cesarean Section / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D007743:Labor, Obstetric; D008423:Maternal Age; D007744:Obstetric Labor Complications / Q000188:drug therapy / Q000601:surgery*; D016017:Odds Ratio; D010121:Oxytocin / Q000627:therapeutic use; D010298:Parity; D011247:Pregnancy; D018566:Pregnancy, High-Risk; D011446:Prospective Studies; D012044:Regression Analysis
chemical_list: D010121:Oxytocin