VASOPRESSIN, ACTH AND NEONATAL HAEMODYNAMICS

Abstract
In 21 normal deliveries, high concentrations of AVP and ACTH in cord blood were associated with higher blood pressure and lower skin temperature, indicating peripheral vasoconstriction. Following Caesarean section after the onset of labour (n = 8), cord AVP concentrations and blood pressures were lower than after normal delivery but higher than after elective Caesarean section (n = 9). Maternal AVP concentrations at delivery were normal, as were plasma AVP concentrations in all infants 3 days after delivery. The relationship between vasopressin, a potential ACTH releasing factor, and ACTH was interesting. We conclude that the massive release of vasopressin is associated with normal delivery, elevated ACTH values and with peripheral vasoconstriction. These findings reflect favourable adaptation to hypoxia and stress of delivery, intended to redistribute cardiac output to vital organs and may provide for physiological adjustments necessary for extrauterine life.