Primary cesarean delivery in the United States.

OBJECTIVES To characterize the indications for primary cesarean delivery in a large national cohort and to identify opportunities to lower the U.S. primary cesarean delivery rate. METHODS A retrospective cohort study of the 38,484 primary cesarean deliveries among the 228,562 deliveries at sites participating in the Consortium on Safe Labor from 2002 to 2008. RESULTS The primary cesarean delivery rate was 30.8% for primiparous women and 11.5% for multiparous women. The most common indications for primary cesarean delivery were failure to progress (35.4%), nonreassuring fetal heart rate tracing (27.3%), and fetal malpresentation (18.5%), although frequencies for each indication varied by parity. Among women with failure to progress, 42.6% of primiparous women and 33.5% of multiparous women never progressed beyond 5 cm of dilation before delivery. Among women who reached the second stage of labor, 17.3% underwent cesarean delivery for arrest of descent before 2 hours and only 1.1% were given a trial of operative vaginal delivery. Of all primary cesarean deliveries, 45.6% were performed on primiparous women at term with a singleton fetus in cephalic presentation. CONCLUSION Using 6 cm as the cut-off for active labor, allowing adequate time for the second stage of labor, and encouraging operative vaginal delivery, when appropriate, may be important strategies to reduce the primary cesarean delivery rate. These actions may be particularly important in the primiparous woman at term with a singleton fetus in cephalic presentation. LEVEL OF EVIDENCE III.