Association of lymphocyte count and incidence of maternal fever in epidural analgesia-involved labor

BACKGROUND: Evidence showed that the use of epidural analgesia increased the risk of maternal fever during labor, and the potential mechanisms involved inflammation. Lymphocyte played a role in the inflammatory responses, and lymphopenia predicted adverse outcomes for patients. The aim of this study was to investigate whether lymphocyte count was associated with the incidence of intrapartum fever in nulliparous women undergoing vaginal delivery. METHODS: In this retrospective cohort study, electronic medical record data at the International Peace Maternity and Child Health Hospital (IPMCH, Shanghai, China) between 2012 and 2017 were extracted. The primary outcome of this study was baseline lymphocyte count in febrile and afebrile parturients who received labor epidural analgesia. Other confounding factors associated with the development of intrapartum fever were analyzed using multivariable logistic regression. RESULTS: The final study population consisted of 36,562 parturients, of whom 18,952 (51.8%) received labor epidural analgesia. Labor epidural analgesia was associated with an increased risk of maternal fever [relative risk: 4.55; 95% confidence interval (CI): 4.16–4.98; P<0.001]. Among the parturients who received epidural analgesia, both baseline lymphocyte count and lymphocyte percentage were lower in the febrile patients than those in the afebrile patients (P<0.001; P=0.015). The lower (<1.1×10(9)/L) baseline lymphocyte was associated with a higher risk of maternal fever (adjusted odds ratio: 1.30, 95% CI: 1.14–1.48; P<0.001). CONCLUSIONS: Our results suggested that lower lymphocyte baseline indicated an increased risk of maternal fever during epidural analgesia-involved labor. Further studies are needed to confirm the findings and determine the potential mechanisms.