Risk of selected postpartum infections after cesarean section compared with vaginal birth: A five-year cohort study of 32,468 women

Objectives. To compare the risk of postpartum infections within 30 days after vaginal birth, emergency, or elective cesarean section (CS). Design. Register-based cohort study in Denmark. Participants. A total of 32,468 women giving birth in hospitals in the County of Aarhus, Denmark, during the period 2001-2005. Methods. Data from various hospital registries were combined and infections were identified by positive cultures, prescriptions for antibiotics and, re-operative procedures. Risk of postpartum infection was estimated and adjustment for potentially confounders was performed. Results. Within 30 days postpartum, 7.6% of women who had underwent CS and 1.6% of women having a vaginal birth acquired an infection, yielding an adjusted odds ratio (OR) of 4.71, 95% confidence interval (CI): 4.08-5.43. The prevalence of postpartum urinary tract infection (UTI) was 2.8%, after CS and 1.5% after vaginal birth corresponding to an adjusted OR=1.68, 95% CI: 1.38 2.03. The risk of UTI did not differ between emergency and elective CS. The prevalence of WI was 5.0% after CS and 0.08% after vaginal birth. Moreover, we found a nearly 50% higher risk of postpartum WI after emergency CS compared to elective CS (OR-1.49, 95% CI: 1.13-1.97). More than 75% (697/907) of postpartum infections appeared after hospital discharge. Conclusions. The risk of postpartum infection seems to be nearly five-fold increased after CS compared with vaginal birth. This may be of concern since the prevalence of CS is increasing.