Epidural analgesia is associated with maternal intra-partum fever during labor. Intermittent epidural injections appear to reduce the incidence of maternal intra-partum fever compared to continuous epidural infusion during labor analgesia. However, the optimal combination of bolus volume and administrating interval has not yet been compared. The purpose of this prospective, randomized, double-blind trial was to determine how intermittent epidural bolus reduced the incidence of maternal intra-partum fever compared with continuous epidural infusion during labor.