ABSTRACT: Catecholamines, epinephrine and norepinephrine, cause characteristic “fight or flight” responses of increased heart rate and blood pressure, vasoconstriction, and other autonomic responses. In animal studies, either injection of Catecholamines or fright causing secretion of these hormones resulted in lower uterine blood flow and fetal bradycardia or acidosis.

Anxious human mothers had weaker contractions and longer labors and higher circulating catecholamine levels. In the presence of lower uterine circulation the normal fetus may compensate by extracting the oxygen needed, while the previously compromised fetus is less able to compensate for the reduced blood supply.