Glucocorticoid regulation of human and ovine parturition: The relationshipbetween fetal hypothalamic-pituitary-adrenal axis activation and intrauterine prostaglandin production

Birth in many animal species and in humans is associated with activation of hypothalamic-pituitary-adrenal function in the fetus and the increased inf luence of glucocorticoids on trophoblast cells of the placenta and fetal me mbranes. We suggest that in ovine pregnancy glucocorticoids directly increa se fetal placental prostaglandin production, and indirectly increase prosta glandin production by maternal uterine tissues through the stimulation of p lacental estradiol synthesis. The events of ovine parturition are compared with those of human parturition. In the latter, we suggest similar direct e ffects of glucocorticoids on prostaglandin synthesis and metabolism in feta l membranes and similar indirect effects mediated by glucocorticoid-stimula ted increases in intrauterine corticotropin-releasing hormone expression.