There was a significant but small reduction in the rate of cesarean delivery from the preintervention period to the postintervention period in the intervention group as compared with the control group ( change , 22.5 % to 21.8 % in the intervention group and 23.2 % to 23.5 % in the control group ; odds ratio for incremental change over time , adjusted for hospital and patient characteristics , 0.90 ; 95 % confidence interval [ CI ] , 0.80 to 0.99 ; P = 0.04 ; adjusted risk difference , -1.8 % ; 95 % CI , -3.8 to -0.2 ) .