Hm. Stein et al., THE EFFECTS OF CORTICOSTEROIDS AND THYROTROPIN-RELEASING-HORMONE ON NEWBORN ADAPTATION AND SYMPATHOADRENAL MECHANISMS IN PRETERM SHEEP, American journal of obstetrics and gynecology, 171(1), 1994, pp. 17-24
OBJECTIVES: We examined the effect of prenatal corticosteroids and thy
rotropin-releasing hormone on postnatal adaptation and sympathoadrenal
function in preterm lambs. STUDY DESIGN: Catheterized fetal lambs rec
eived saline solution (n = 6), corticosteroids alone (n = 8), or corti
costeroids plus thyrotropin-releasing hormone (n = 6) for 60 hours. Th
e lambs were delivered by cesarean section at a gestational age of 130
+/- 1 days. Ventilatory, cardiovascular, and metabolic responses and
plasma catecholamine concentrations were measured for 2 hours after bi
rth. Statistical anaysis was performed by use of independent t tests o
r analysis of variance. RESULTS: Ventilatory function and cardiac cont
ractility were significantly improved in both corticosteroid and corti
costeroid plus thyrotropin-releasing hormone animals. Lambs treated wi
th corticosteroid plus thyrotropin-releasing hormone had significantly
higher aortic pressure and left ventricular blood pressure than eithe
r of the other groups. The postnatal norepinephrine and epinephrine su
rge was blunted in response to corticosteroid and corticosteroid plus
thyrotropin-releasing hormone treatment. There were no differences in
metabolic responses among the three groups. CONCLUSIONS: In premature
lambs prenatal exposure to corticosteroids and thyrotropin-releasing h
ormone improves postnatal cardiovascular adaptation more than corticos
teroids alone.