[Beta-endorphin in premature labor and in mature newborn infants following vaginal and abdominal delivery].

Umbilical venous plasma concentrations of beta-endorphin in 20 premature and 30 mature newborn infants after vaginal delivery or elective caesarean section were determined by specific RIA. In the premature infants the beta-endorphin levels after vaginal and abdominal delivery were significantly higher than in mature newborns. Our data indicate that for premature infants the delivery is more stressful and therefore most likely the release of beta-endorphin from the pituitary is more pronounced. Since high opioid levels can cause respiratory and circulatory difficulties, premature infants are exposed to risk of these problems.