Administration of anesthetic solution into the epidural space is usually accomplished by a combination of continuous infusion, provider-administered boluses and patient-administered boluses (patient controlled epidural analgesia [PCEA]). The optimal method for maintaining labor analgesia is unknown. Several studies have demonstrated that timed-intermittent boluses, in combination with patient-controlled epidural analgesia (PCEA), provide superior maintenance of labor analgesia than maintenance with a continuous infusion with PCEA. Epidural infusion pumps capable of delivering timed boluses of local anesthetic with PCEA recently became commercially available. Several infusion rates are available for delivering the timed bolus, and the optimal bolus rate is unknown.