Vasopressin and oxytocin levels in human neonates. Relationships with the evolution of labour and beta-endorphins.

In order to find out whether arterial and venous cord levels of vasopressin (VP) and oxytocin (OT) might be linked to one or more obstetric parameters and to beta-endorphin (BEP) secretion, 42 successively delivered neonates were studied. Arterial and venous cord blood levels of these peptides were not statistically different whenever the neonates were born vaginally with or without foetal distress, after induction of labour by oxytocic drugs, or by elective caesarean section. BEP levels in cord and maternal blood do not seem to be linked with AVP or OT. The results of the group of infants born after uncomplicated vaginal delivery analyzed with regard to obstetric parameters, led to the following conclusions: arterial cord VP correlated with venous cord VP, with arterial cord OT and with the duration of membrane rupture; arterial cord OT correlated with venous cord OT and with the time taken by the cervix to dilate from 5 to 10 cm, suggesting that the foetal pituitary gland is sensitive to the evolution of labour.