Ropivacaine versus bupivacaine for epidural labour analgesia: a retrospective cohort analysis of intrapartum maternal fever

Objective To compare the relative associations of ropivacaine and bupivacaine for epidural labour analgesia with the incidence of intrapartum maternal fever (IMF) in a retrospective cohort. Methods This single-centre retrospective cohort study included 5,666 parturients receiving epidural analgesia for vaginal delivery. Patients were grouped by the local anaesthetic used in patient-controlled epidural analgesia: ropivacaine ( n = 2,989) or bupivacaine ( n = 2,677). The primary outcome was IMF, defined as an axillary temperature ≥ 38.0 °C. Multivariable logistic regression was used to assess the association between local anaesthetic type and IMF, adjusting for parity and maternal and obstetric covariates. Results Intrapartum maternal fever occurred in 564 parturients (10.0%). After adjustment, bupivacaine use was associated with a lower risk of IMF compared with ropivacaine (adjusted odds ratio [OR] 0.744, 95% confidence interval [CI] 0.621–0.892, P < 0.001). Multiparity was independently associated with a lower risk of fever (adjusted OR 0.278, 95% CI 0.207–0.373, P < 0.001). The association between local anaesthetic type and fever was consistent across subgroups stratified by parity and membrane status (all interaction P > 0.05). Conclusion In this retrospective cohort study, bupivacaine for labour epidural analgesia was associated with a lower incidence of intrapartum maternal fever compared with ropivacaine. These findings suggest a potential association that warrants further investigation. However, due to the observational, epoch-based design, causality cannot be established, and the results should not be interpreted as evidence to change current clinical practice. Prospective randomised trials are required to confirm these findings.