Objective: To examine regional variations in rates of primary cesarean delivery and assisted vaginal delivery in the population of British Columbia, while adjusting for the maternal characteristics and conditions that increase the likelihood of operative delivery.
Methods: Using data from the British Columbia Perinatal Database Registry, we studied all deliveries in British Columbia between 2004 and 2007, excluding women who had a previous cesarean delivery (n=116,839). Our primary outcome of interest was mode of delivery, further defined as delivery by cesarean or assisted vaginal delivery. We calculated crude and risk-adjusted rates of primary cesarean delivery and assisted vaginal delivery across British Columbia's 16 Health Service Delivery Areas and examined cesarean delivery rates by indication for the procedure.
Results: Crude primary cesarean delivery and assisted vaginal delivery rates varied markedly across the Health Service Delivery Areas ranging from 16.1 to 27.5 per 100 deliveries, and from 8.6 to 18.6 per 100 deliveries, respectively. The most common indication for cesarean delivery was dystocia, which accounted for 30.0% of all cesarean deliveries and varied more than fivefold across regions. After controlling for maternal characteristics and conditions known to increase the likelihood of cesarean delivery and assisted vaginal delivery, adjusted cesarean delivery rates varied twofold, ranging from 14.7 to 27.6 per 100 deliveries, while adjusted assisted vaginal delivery rates varied by more than twofold, ranging from 6.5 to 15.3 per 100 deliveries.
Conclusion: Our results illustrate substantial regional variation in the use of cesarean delivery that cannot be explained by patient illness or preferences. This variation likely reflects differences in practitioners' approaches to medical decision-making.
Level of evidence: II.