Obstetric analgesia and immunoreactive endorphin peptides in maternal plasma during labor

We studied the effect of obstetric analgesia on maternal plasma levels of immunoreactive endorphin peptides (ir-EP) during labor and the postpartum period in three groups of parturients: group I (n = 22) had no analgesia, group II (n = 20) received pethidine intramuscularly, and group III (n = 10) had continuous epidural analgesia. Initial levels of ir-EP were similar in all three groups. Patients without any medication and patients on pethidine showed a significant rise in ir-EP in late labor and at delivery. Epidural analgesia was characterized by constant levels of ir-EP during labor and an insignificant rise at delivery.