Aim of the study To detect the optimal dose of bupivacaine and levobupivacaine in the aspects of efficiency and safety when patient controlled epidural analgesia is used for labor pain management. Objectives of the study: 1. To detect the demand of bupivacaine and levobupivacaine total dose and hourly consumption when different concentrations of that drugs are used for labor pain management with patient controlled epidural analgesia; 2. To detect the efficiecy of labor pain management, when different concentrations of bupivacaine and levobupivacaine are used for labor pain analgesia, and pain level is evaluated using verbal analogue scale score, the frequency of pain breakthroughs and rescue boluses and the request of patient controlled analgesia; 3. To eveluate the influence of different concentrations of bupivacaine and levobupivacaine, used for labor pain management with patient controlled epidural analgesia, on the course and the mode of delivery and the maternal side effects; 126 4. To detect the effect of different concentrations of bupivacaine and levobupivacaine, used for labor pain management with patient controlled epidural analgesia, on the state of fetus and new-born; 5. To evaluate the effect of different concentrations of bupivacaine and levobupivacaine, used for labor pain management with patient controlled epidural analgesia, on the parturients satisfaction with labor analgesia and to detect the factors that influence the satisfaction with labor analgesia.[...].