Objective: To evaluate the variables associated with changes in cesarean delivery (CD) rates in a University Hospital with standardized and unchanged protocols of care.
Methods: Retrospective analysis of consecutive deliveries between two triennia 10 years apart. The Robson classification of CD was used, and the analysis focused on factors affecting Robson's classes 1 and 2 combined (term singleton cephalic nulliparae) and class 5 (previous CD).
Results: A total of 8237 deliveries occurred in the 1st period, and 8420 in the 2nd. CD increased from 12.5 to 18% (p < 0.001). Robson's classes 1 and 2 combined contributed more than other classes to CD rates (32 vs 36%; p < 0.001). At multivariate analysis, BMI (Odds ratio [OR]: 1.08; 95% CI: 1.06-1.1) and maternal age (OR: 1.06; 95% CI: 1.05-1.08) were independently related to CD. In Robson class 5, the rate of CD increased from 34 to 46%, p < 0.001, mostly due to an increase in elective CD (39 vs 67.5%; p < 0.001). At multivariate analysis, BMI (OR: 1.06 95% CI: 1.02-1.1) and more than one previous CD (OR: 18.7; 95% CI: 9.6-36.4) were independently related to CD.
Conclusions: BMI and maternal age are independent factors associated to the increasing rate of CD in nulliparae with spontaneous or induced labor at term. In women with previous CD, BMI and more than one previous CD are factors associated with the increasing rate of CD.