title: Varying gestational age patterns in cesarean delivery: an international comparison.
abstract: BACKGROUND
  While international variations in overall cesarean delivery rates are well documented, less information is available for clinical sub-groups. Cesarean data presented by subgroups can be used to evaluate uptake of cesarean reduction policies or to monitor delivery practices for high and low risk pregnancies based on new scientific evidence. We studied differences and patterns in cesarean delivery rates by multiplicity and gestational age in Europe and the United States.
  
  
  METHODS
  This study used routine aggregate data from 17 European countries and the United States on the number of singleton and multiple live births with cesarean versus vaginal delivery by week of gestation in 2008. Overall and gestation-specific cesarean delivery rates were analyzed. We computed rate differences to compare mode of delivery (cesarean vs vaginal birth) between selected gestational age groups and studied associations between rates in these subgroups namely: very preterm (26-31 weeks GA), moderate preterm (32-36 weeks GA), near term (37-38 weeks GA), term (39-41 weeks GA) and post-term (42+ weeks GA) births, using Spearman's rank tests.
  
  
  RESULTS
  High variations in cesarean rates for singletons and multiples were observed everywhere. Rates for singletons varied from 15% in The Netherlands and Slovenia, to over 30% in the US and Germany. In singletons, rates were highest for very preterm births and declined to a nadir at 40 weeks of gestation, ranging from 8.0% in Sweden and Norway, to 22.5% in the US. These patterns differed across countries; the average rate difference between very preterm and term births was 43 percentage points, but ranged from 14% to 61%. High variations in rate differences were also observed for near term versus term births. For multiples, rates declined by gestational age in some countries, whereas in others rates were similar across all weeks of gestation. Countries' overall cesarean rates were highly correlated with gestation-specific subgroup rates, except for very preterm births.
  
  
  CONCLUSIONS
  Gestational age patterns in cesarean delivery were heterogeneous across countries; these differences highlight areas where consensus on best practices is lacking and could be used in developing strategies to reduce cesareans.
authors.affiliation: INSERM UMR1153, Obstetrical, Perinatal and Pediatric Epidemiology Research Team, Research Center for Epidemiology and Biostatistics Sorbonne Paris Cité (CRESS), DHU Risks in pregnancy, Paris Descartes University, Port Royal Maternity Unit, 53 Avenue de l'Observatoire, Paris, 75014, France. marie.delnord@inserm.fr.
authors.forename: Marie
authors.initials: M
authors.lastname: Delnord
authors.forename: Béatrice
authors.initials: B
authors.lastname: Blondel
authors.forename: Nicolas
authors.initials: N
authors.lastname: Drewniak
authors.forename: Kari
authors.initials: K
authors.lastname: Klungsøyr
authors.forename: Francisco
authors.initials: F
authors.lastname: Bolumar
authors.forename: Ashna
authors.initials: A
authors.lastname: Mohangoo
authors.forename: Mika
authors.initials: M
authors.lastname: Gissler
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Szamotulska
authors.forename: Nicholas
authors.initials: N
authors.lastname: Lack
authors.forename: Jan
authors.initials: J
authors.lastname: Nijhuis
authors.forename: Petr
authors.initials: P
authors.lastname: Velebil
authors.forename: Luule
authors.initials: L
authors.lastname: Sakkeus
authors.forename: James
authors.initials: J
authors.lastname: Chalmers
authors.forename: Jennifer
authors.initials: J
authors.lastname: Zeitlin
mesh_terms: D002585:Cesarean Section / Q000706:statistics & numerical data*; D005060:Europe; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007233:Infant, Postmature; D050498:Live Birth; D011247:Pregnancy; D011272:Pregnancy, Multiple / Q000706:statistics & numerical data; D047928:Premature Birth / Q000601:surgery; D047929:Term Birth; D014481:United States