Glucocorticoid stimulation of blood coagulation factor activities in the fetal lamb

Blood coagulation factor activities, including factors II, VII, IX, X, XI, and XII, are lower than normal in full-term infants and more severely depressed in premature infants. Previous studies in our laboratory using a fetal lamb model indicated that most coagulation factor activities increase during the latter part of the third trimester of pregnancy. Since glucocorticoid stimulation of the fetus accelerates fetal lung maturation in experimental models and in offsprings of mothers with impending premature labor, we hypothesized that glucocorticoid stimulation might induce increases in blood coagulation factor activities similar to those found near term. Two sets of experiments were carried out in chronically catheterized fetal lambs early in the third trimester (100 to 120 days gestation). In one set of experiments, one twin from each of 10 twin sets was infused with hydrocortisone (2 mg/hr for 48 hr). The twin sibling served as a control. In the other set of experiments, six pregnant ewes were given 15 mg of beta-methasone intramuscularly every 24 hr for two doses. Five pregnant ewes were injected with saline and used as controls. Fetal blood samples were obtained prior to and 48 hr after the start of the hydrocortisone infusions and prior to and 24 hr after the second dose of beta-methasone given to the pregnant ewes. The results of blood coagulation factor activities comparing glucocorticoid-stimulated fetuses with controls demonstrated significant increases in the activities of blood coagulation factors II, V, VII, IX, and X in the stimulated fetuses. There were no significant changes in the activities of factors VIII, XI, or XII. The results confirmed the hypothesis that glucocorticoid stimulation increases many blood coagulation factor activities in the fetus.