title: Cesarean section and maternal education; secular trends in Norway, 1967-2004.
abstract: BACKGROUND
  Worldwide rising cesarean section rates over the past decades have caused much concern. Studies on the association between cesarean section and maternal social background have reported conflicting results.
  
  
  METHODS
  A cohort study, comprising 837,312 birth order one deliveries notified to the population-based Medical Birth Registry of Norway during 1967-2004. The relative risk of cesarean section (from 1988 onwards planned and emergency cesarean section) according to maternal educational level was assessed in all deliveries, in an obstetric low-risk group and within groups of medical/obstetric high-risk conditions.
  
  
  RESULTS
  Throughout the study period, the lowest educated had the highest risk of cesarean section, followed by the medium educational group. In all deliveries, the adjusted relative risk of cesarean section for the lowest versus the highest educated increased from 1.16 (95% CI 1.09-1.23) in the 1967-76 period to 1.34 (95% CI 1.27-1.42) in the 1996-2004 period, and in the obstetric low risk group from 1.19 (95% CI 1.10-1.30) to 1.50 (95% CI 1.38-1.63). From 1988 onwards, the lowest educated had the highest risk of both planned and emergency cesarean section, followed by the medium educational group.
  
  
  CONCLUSIONS
  The lowest educated had the highest risk of cesarean section, followed by the medium educational group, and the differences gradually increased during 1967-2004. This trend could be accounted for by increasing vulnerability of the lowest educational group due to a strong social migration, and by increased occurrence of cesarean section on maternal request among the lowest educated in recent years.
authors.affiliation: Section for Epidemiology and Medical Statistics, Department of Public Health and Primary Health Care, University of Bergen, Norway. mette.tollanes@isf.uib.no
authors.forename: Mette C
authors.initials: MC
authors.lastname: Tollånes
authors.forename: John M D
authors.initials: JM
authors.lastname: Thompson
authors.forename: Anne K
authors.initials: AK
authors.lastname: Daltveit
authors.forename: Lorentz M
authors.initials: LM
authors.lastname: Irgens
mesh_terms: D000328:Adult; D002585:Cesarean Section / Q000706:statistics & numerical data* / Q000639:trends; D015331:Cohort Studies; D004522:Educational Status; D005260:Female; D006801:Humans; D009664:Norway; D011247:Pregnancy; D012189:Retrospective Studies; D012306:Risk