Abstract
BACKGROUND: Sterile inflammation is a key factor in epidural-related maternal fever (ERMF). While antepartum changes in white blood cell counts have been associated with ERMF, their impact on the occurrence of ERMF remains poorly understood. OBJECTIVE: To examine the relationship between lymphocyte-to-monocyte ratio (LMR) and ERMF and to assess the potential impact of LMR on ERMF onset in parturients. METHODS: This prospective cohort study included 543 parturients who underwent labor epidural analgesia at the Guangdong Women and Children Hospital from January 2022 to September 2024. ERMF was defined as a maternal temperature of ≥ 38 °C on a single occasion or two readings of ≥ 37.5 °C taken 1 h apart. Univariate and multivariate logistic regression models were utilized to explore the association between LMR level and ERMF. Receiver operating characteristic curve analysis was conducted to determine the optimal cutoff value for the LMR associated with ERMF. The Kaplan-Meier curve and log-rank test were used to compare the time to ERMF onset between parturients with higher and lower LMR levels. RESULTS: Totally, 543parturients, 20.4% of whom developed ERMF. Lower LMR was associated with an increased incidence of ERMF (adjusted OR = 0.50, 95% CI: 0.36-0.69, P < 0.001). ROC curve analysis identified an antepartum maternal LMR level ≤ 2.37 as an associative cutoff for ERMF. Compared with parturients with an LMR > 2.37, those with an LMR ≤ 2.37 exhibited a significantly higher odds of developing ERMF (adjusted OR = 5.43, 95% CI: 3.18-9.28, P < 0.001). The onset time of ERMF was shorter in the lower LMR group but did not reach statistical significance (230.6 ± 15.3 min vs. 261.2 ± 18.4 min, P = 0.088). Among parturients exhibiting ERMF, a significantly higher rate of temperature rise to ERMF was observed in parturients with a lower LMR level (0.37 [0.29, 0.55] °C/h vs. 0.31 [0.20, 0.53] °C/h, P = 0.013). CONCLUSION: Low LMR levels were observed to be associated with an increased risk of ERMF. TRIAL REGISTRATION: ChiCTR2200055734 on January 16, 2022.