Elevated pulse perfusion index values and interleukin-6 levels as associated factors for epidural-related maternal fever: a nested case‒control study

To date, the mechanism of epidural-related maternal fever (ERMF) remains unclear. Studies have pointed to various noninfectious factors linked to ERMF, yet relevant conclusions remain inconsistent. This study aimed to investigate whether the elevated pulse perfusion index (PI) and interleukin-6 (IL-6) were associated with ERMF and further evaluated their interactive biological effects. A total of 100 parturients receiving epidural analgesia were analyzed in this unmatched nested case ‒ control study on the basis of a cohort study conducted within ten months. Baseline characteristics and intrapartum data were collected. Maternal blood samples were taken at admission (T 1 ), before epidural analgesia (T 2 ), and at the end of the second stage of labor (T 3 ). Plasma was isolated to detect IL-6 concentrations. PI on the second toe of the right foot was monitored continuously. The PI 30 min after labor analgesia (PI 30 ) was determined. Binary logistic regression and Andersson’s interaction model were adopted to identify independent factors associated with ERMF. Analysis revealed that elevated PI 30 (≥ 9.30) and high levels of IL-6 at T 3 (≥ 50.07 pg/mL) were significantly associated with an increased risk of developing ERMF, with corresponding odds ratios (ORs) of 3.697 and 5.031, respectively. No statistically significant biological interaction was detected between PI 30 and T 3 IL-6 on the incidence rate of ERMF. Elevated PI 30 (≥ 9.30) and T 3 IL-6 (≥ 50.07 pg/ml) were each independently associated with ERMF, with no significant interaction detected between the two factors. .Targeted modulation of the two factors is hypothesized as a possible approach to lower ERMF incidence.