Plasma immunoreactive beta-endorphin, ACTH and cortisol concentrations in mothers and their neonates immediately after delivery--their relationship to the duration of labor.

In 29 cases of vaginal delivery with normal outcome and 4 cases of cesarean section, the concentrations of beta-endorphin, ACTH and cortisol were determined in maternal venous and umbilical venous plasma immediately postpartum. According to duration of labor and mode of delivery the cases examined were classified into three groups: Group A (18 cases) = vaginal delivery of less than 10 hours' duration, Group B (11 cases) = vaginal delivery of more than 10 hours' duration of labor, Group C (4 cases) = cesarean section under general anesthesia. With the exception of one, the deliveries took place at term. The 33 neonates were in a very good clinical state 5 minutes after parturition (11 Saling points as median value). For measurement of the hormone concentrations radioimmunoassays were used. In Group a the mean beta-endorphin concentration in maternal plasma amounted to 150.9 +/- 16.3 pg/ml, that in neonatal plasma to 239.2 +/- 23.5 pg/ml (means +/- SEM). In Group B plasma beta-endorphin, both maternal and neonatal, was slightly higher than in Group A: 153.0 +/- 12.0 pg/ml (maternal) and 260.9 +/- 37.1 pg/ml (neonatal). The differences between maternal and neonatal beta-endorphin levels were statistically significant: Group A p less than 0.01, Group B p less than 0.05; chi 2-test. The mean ACTH concentrations in the plasma of the newborn infants were also found to be considerably higher compared with those in the plasma of their mothers: Group A 78.2 +/- 16.5 pg/ml (maternal) and 98.0 +/- 23.3 pg/ml (neonatal); Group B 98.0 +/- 20.1 pg/ml (maternal) and 165.8 +/- 39.6 pg/ml (neonatal).(ABSTRACT TRUNCATED AT 250 WORDS)