ADRENOCORTICOTROPIC HORMONE IN HUMAN FETAL BLOOD AT DELIVERY

ACTH concentrations in umbilical arterial and venous plasma were measured in newborn infants delivered both vaginally and by cesarean section. Mean ACTH was significantly higher in the arterial (602.0 pg/ml) than venous (261.5 pg/ml) plasma in vaginal deliveries (P < 0.01). Arterial plasma of babies born by elective cesarean section before initiation of labor contained less ACTH (384.7 pg/ml) when compared to those delivered after labor had started (698.7 pg/ml). Serial determinations of ACTH in pooled fetal blood obtained during labor showed that the average hormone titers increased significantly from 1st stage (295.2 pg/ml) to 2nd stage of labor (440.5 pg/ml) and reached a peak at delivery (645.4 pg/ml). The pituitary gland of the fetus at midtrimester contained ACTH. Possible mechanisms for fetal secretion of ACTH at delivery are discussed.