Background: One of the most painful situations that a woman may experience is labor. On the other hand, except for some indicated cases, cesarean has been proved to be dangerous for mother. The pain of uterus contractions can be diminished by epidural analgesia. Maternal Catecholamine increases during labor and epidural anesthesia reduces Epinephrine level and increases uterine blood flow . The purpose of the present study was to evaluate the effect of epidural analgesia on Epinephrine concentration and duration of first stage of labor.

Materials and Methods: Using clinical trial method, we considered 100 healthy parturient primigravid with single fetus and ≥ 4 cm cervix dilatation without major medical complication for epidural anesthesia with 10 ml Lidocaine 5% (50 patients) or 50 mg IV Mepridin (50 patients). Then venous blood samples (5 cc) were obtained from all patients at the end of first stage of labor. All samples were analyzed by a Radio enzymatic assay for Epinephrine level. T test, colmograph and smirnof tests were used for data analysis. 

Results: Plasma epinephrine levels in Mepridin and epidural groups were 95.9±22.2 and 41.4±15.4 pg/ml respectively (P<0.0001), showing decreased in epidural group. Duration of first stage of labor (active phase) in Mepridin and epidural groups were 166.6±25.1 min and 153.8±26 min respectively. Duration of first stage (active phase) was shorter in Epidural group (P<0.02).

Conclusion: Lumbar epidural anesthesia during labor Reduces maternal Epinephrine level and duration of first stage of labor (active phase.) Epidural anesthesia is an effective method of analgesia in labor.