In the early 1990s, the Department of Health and Human Services identified the need to reduce the cesarean rate. Despite national goals 7,8 and recommendations from the American College of Obstetricians and Gynecologists,9 the national cesarean delivery rate has steadily increased since 1996; in 2009, one third of all women who gave birth had a cesarean delivery.2 To achieve the overall goal of reducing unwarranted cesarean deliveries, we need a more comprehensive understanding of the influence of medical and nonmedical factors on operative delivery.