cosyntropin and Pregnancy--Prolonged

In the fetal rat, plasma corticosterone concentration (PCC) decreases dramatically on the 20th day of gestation and remains low until birth even if the parturition is delayed until 23.5 days postcoitus. In the normal term newborn, there is an increase of PCC in the 1st h after birth. In postmature newborn rats this increase is not present but PCC can be increased towards normal term values if the adrenal cortex is stimulated with cosyntropin or lysine-vasopressin. This suggests that the lack of elevation of PCC in the postmature newborn is not due to the lack of responsiveness of the adrenal cortex but rather an impairment of the hypophyseal stimulation. The absence of PCC elevation at birth could contribute to the metabolic disorders observed in the postmature newborn rat.

Topics: Animals; Animals, Newborn; Corticosterone; Cosyntropin; Female; Fetal Blood; Gestational Age; Kinetics; Lypressin; Pregnancy; Pregnancy, Prolonged; Rats

Diminished total plasma cortisol levels have been demonstrated in postmature neonates, suggesting that fetal glucocorticoids may be involved in the cause of postmaturity. This hypothesis was tested by adrenocortical stimulation in 32 newborns: 12 were postmature; 12 were postterm, but not postmature; and 8 were normal term neonates. The mean pre- and poststimulation total plasma cortisol levels were 3.9 and 50.9 microgram/100 ml, respectively, for the postmature newborns, 9.7 and 44.0 microgram/100 ml for the postterm, but nonpostmature newborns, and 9.8 and 37.1 microgram/100 ml for the normal term newborns. The differences in the poststimulation rise in plasma cortisol between the postmature and merely postterm infants or between the postterm and normal term infants were not statistically significant. The mean poststimulation cortisol rise in the postmature group exceeded that of the normal term group (P less than 0.05). The adequacy and promptness of response to adrenocortical stimulation eliminate the likelihood of adrenal insufficiency in postmature infants.

Topics: Adrenal Cortex; Adrenal Cortex Diseases; Adrenocorticotropic Hormone; Cosyntropin; Female; Humans; Hydrocortisone; Infant, Newborn; Placenta Diseases; Pregnancy; Pregnancy, Prolonged