Labor pain effects on colostral milk beta-endorphin concentrations of lactating mothers.

beta-Endorphin (beta-EP) levels of colostral milk are approximately two-fold higher than in plasma of lactating women, in who concentrations peak at term, after the first and second stages of labor. We investigated the effect of labor pain and vaginal parturition on colostral beta-EP concentrations (beta-endorphin (125)I RIA, Incstar Corp., Stillwater, Minn., USA) of at-term nursing mother, in comparison to those having undergone elective cesarean section. Our results show that colostral milk beta-EP concentrations of mothers who delivered vaginally are significantly higher on the 4th postpartum day (6.0 +/- 0.5 vs. 4.3 +/- 0.4 pmol/l, respectively; p < 0.01) than colostral levels of mothers who underwent cesarean section. These data indicate the important influence of the labor process on the colostral opioid galactopoiesis. It is suggested that labor and parturition pain may increase colostral milk beta-EP concentrations of lactating mothers in order to help the newborn overcome the stressful perinatal events of natural labor and delivery. Copyright 2001 S. Karger AG, Basel