Labor and delivery outcomes with remifentanil patient-controlled analgesia versus labor epidural analgesia among women with and without obesity: a retrospective population-based cohort study (2015–2024)

Background Evidence regarding the safety and effectiveness of remifentanil patient-controlled analgesia (RPCA) in women with obesity remains limited. We compared labor and delivery outcomes associated with RPCA and labor epidural analgesia (LEA) according to maternal body mass index (BMI). Methods This retrospective population-based cohort study included women with singleton, term, cephalic pregnancies undergoing spontaneous or induced labor who received either RPCA or LEA in Slovenia between 2015 and 2024. Analyses were performed separately in women with BMI < 30 kg/m 2 and ≥ 30 kg/m 2 . Multivariable logistic regression was used to adjust for relevant maternal and obstetric confounders. Primary outcomes were intrapartum cesarean delivery and operative vaginal delivery. Results A total of 52,118 women were included, of whom 46,448 had BMI < 30 kg/m 2 and 5670 had BMI ≥ 30 kg/m 2 . RPCA was associated with lower risks of intrapartum cesarean delivery and operative vaginal delivery than LEA in both BMI strata (all P ≤ 0.001). In contrast, RPCA was associated with higher risks of postpartum hemorrhage across both BMI groups, and among women with BMI < 30 kg/m 2 , higher risks of blood transfusion and third- or fourth-degree perineal tears. Neonatal outcomes were otherwise comparable between groups. In women with BMI < 30 kg/m 2 , RPCA was associated with lower odds of an Apgar score < 7 at 1 min, although no differences were observed at 5 min, in neonatal intensive care unit admission, or in perinatal asphyxia. Conclusions In this large, population-based cohort, RPCA was associated with lower risks of intrapartum cesarean delivery and operative vaginal delivery than LEA irrespective of maternal BMI, without evidence of increased neonatal morbidity. These findings, derived from an observational study, should be interpreted cautiously given the potential for residual confounding and selection bias, and further prospective studies are required to clarify the causal relationships between analgesic technique and labor outcomes.