Objective:To evaluate the efficacy of long-interval programmed intermittent epidural bolus (PIEB) during the incubation period for labor analgesia.Methods:Seventy-eight nulliparous parturients who were at full term with a singleton fetus in vertex presentation, aged 22-35 yr, with body mass index of 18.0-30.0 kg/m 2, of American Society of Anesthesiologists physical statusⅠorⅡ, were divided into 2 groups ( n=39 each) using a random number table method: routine epidural bolus using a stepwise approach group (C group) and long-interval PIEB group (L group). Epidural puncture was performed at L 2, 3, and the analgesia solution was 0.1% ropivacaine and 0.5 μg/ml sufentanil in the two groups.The parturients in group C received 8 ml pulse dose per hour during the incubation period (cervical dilatation <3 cm), and 10 ml pulse dose per hour during the active phase (cervical dilatation ≥3 cm). In group L, the first pulse dose was 10 ml during the incubation period, 1.5 h later the anesthesia plane was detected, and 10 ml pulse dose was immediately given when the plane was lower than T 10, otherwise it was reevaluated 15 min later.After the interval time reached 2 h, a pulse dose 10 ml was given regardless of whether the plane was lower than T 10, and the pulse dose 10 ml was given at 1 h interval during the active phase.The numerical rating scale scores were recorded when the cervical dilatation was 3, 6 and 10 cm, and at the time of baby delivery.The duration of labor, total consumption of analgesics, and Bromage grade of lower extremities were recorded.The Apgar score <7 at 1 and 5 min after birth was recorded.The maternal adverse reactions and scores for satisfaction with analgesia were also recorded. Results:Thirty puerperae were finally enrolled in each group.The first stage of labor and total duration of labor were significantly shortened, and the total consumption of analgesics was decreased in group L ( P<0.01). There were no significant differences in the numerical rating scale scores at each time point, duration of second and third stages of labor, Bromage grade of lower extremities, incidence of adverse reactions, score for satisfaction with analgesia, and incidence of Apgar score < 7 after birth between the two groups ( P>0.05). Conclusions:When PIEB is used for labor analgesia, prolonging the infusion interval time of epidural bolus to 1.5-2.0 h during the incubation period can produce satisfactory analgesic effect and further decrease the consumption of analgesics and reduce the influence on labor stages when compared with administration using a stepwise approach.