Abstract
INTRODUCTION: Labor epidural analgesia (LEA) is widely used for intrapartum pain management, but its effects on uterine activity (UA) remain unclear. Electrohysterography (EHG) is a promising non-invasive method for intrapartum UA monitoring. The aim of this study was to explore the effect of LEA on UA by means of EHG, to develop better understanding of labor physiology, and inform clinical decision-making. MATERIAL AND METHODS: Patients in active labor with singleton, term pregnancies who received electrophysiological monitoring from 60 min before until 120 min after LEA initiation were included. Contraction parameters such as frequency, duration, area under the curve (AUC), baseline, and maximum amplitude were obtained from an EHG-derived tocogram using a computer-based algorithm. The primary outcome was the difference in mean uterine contraction frequency before and after initiation of LEA. Secondary outcomes included the comparison of various contraction parameters, derived from EHG, before and after LEA initiation, as well as their temporal changes over time. The effect of possible confounders on UA was examined. Mixed effects models were used for statistical analyses. RESULTS: In total, 86 patients were included. No significant difference in mean uterine contraction frequency and contraction duration was found before and after LEA initiation. Nevertheless, start of LEA was associated with a significant reduction in AUC, baseline activity, and signal amplitude. CONCLUSIONS: LEA initiation does not affect uterine contraction frequency or duration, but it is associated with a significant reduction in relative EHG-derived amplitude parameters (AUC, baseline tone, and maximum amplitude), which could potentially affect progression of labor. Further studies are required to explore these parameters and their clinical implications.