PLASMA-LEVELS OF BETA-ENDORPHIN AND ACTH DURING LABOR AND IMMEDIATE PUERPERIUM

We measured concentrations of beta-endorphin (beta-EP) and adrenocorti cotropic hormone (ACTH) in maternal peripheral plasma during dilation, the expulsive period and immediate puerperium, and in the umbilical v ein. Plasma levels of both peptides increased markedly and were direct ly correlated during labor, and decreased 24 hr after birth; they were no longer correlated during immediate puerperium. In the umbilical ve in, beta-EP and ACTH were also directly correlated. Moreover, the conc entration of each of the two peptides in maternal plasma during the ex pulsive period was correlated with the corresponding concentration in umbilical vein. We discuss the importance of placental corticotropin-r eleasing factor in the regulation of maternal and fetal stress.