The relationship between maternal relaxation and plasma beta-endorphin levels during parturition.

beta-endorphin (beta-EP) levels increase in maternal plasma starting from the 10th to the 12th week of pregnancy and reach a peak during labor and at delivery. Respiratory autogenous training (RAT) has been acclaimed as one of the most effective non-pharmacological methods of obtaining hypoalgesia and relaxing perineal muscles during labor. In order to study the effects of the RAT method in both maternal and fetal beta-EP levels during labor, 28 pregnant women were enrolled in this study. Fourteen attended a RAT program, while the others (control group) did not. beta-EP levels in both groups were measured in maternal plasma at early and late labor, at delivery and on the 4th day of the puerperium and in umbilical cord blood at birth. From late labor on, beta-EP maternal plasma levels increased significantly less in the RAT group than in the control group. The gap in the beta-EP levels between both groups was still significant at puerperium and in umbilical cord blood. In conclusion, the RAT method favorably modulates the secretion of beta-EP during labor and at delivery. This result supports the effectiveness of the RAT method in reducing both maternal and fetal stress during labor.