Although the benefits of antenatal hormone treatment are well accepted, most studies have reported only pulmonary effects. There is evidence of beneficial cardiovascular and metabolic effects in studies using chronically catheterized animals; however because of the route of administration, the results are not directly applicable to clinical strategies. We previously demons trated sign ificant pulmonary effects in animals treated antenatally with a single, direct fetal, intramuscular injection of glucocorticoids . Th is study was performed to determine the effects of a single fetal injection of betamethasone (BETA) alone or in combination with thyroxine (T 4 ) on cardiovascular and metabolic respons es after preterm birth . Hemodynamic and metabolic response s at birth were determined in fetuses (126-d gestation; term = 150 d) treated with ultrasound-guided intramuscular injections of 0.5 mg/kg BETA (n = 7), BETA plus 60 g/kg T 4 (n = 7), or saline (SAL, n = 9). After 48 h, lambs were delivered by cesarean section and studied for 3 h. BETA treatment increased mean arterial blood pressure [56 ± 6 (SEM) versus 42 ± 3 mm Hg], heart rate (152 ± 5 versus 123 ± 4 beats/min), and cardiac Multiple studies have documented improved outcomes of preterm human infants born to mothers treated antenatally with glucocor ticoids. Most studies have focused primarily on pulmonary effects, although secondary outcome variables and retrospective metanalysis of clinical and other demographic data indicate beneficial effects in other organ systems (1, 2). Maternal corticosteroid treatment reduces nonrespiratory morbidities such as intraventricular hemorrhage, necrotizing enterocolitis, and patent ductus arteriosus. The mechanism(s) for these varied clinical outcomes is uncertain .In previous studies using chronically catheterized fetal sheep we demonstrated that antenatal corticosteroid infusion signifi- Responses of BETA + T 4 -treated animals were not different from animals treated with BETA alone. Glucose and FFA were simila r among all groups. The increase in catecholamine levels normally seen at birth was significantly attenuated in both the BETA and BETA + T 4 -treated animal s. A single, intramuscular injec tion of glucocorticoids 48 h before delive ry improves cardiovascular responses to preterm birth . This effect is not augmented by concomitant admi nistration of T4 ' (Pediatr Res 38: 709-715, 1995) Abbrev iations BETA, betamethasone T 4 , thyroxine T 3 , triiodothyronine SAL , saline TRH, thyrotropin-releasing hormone ANOVA, analysis of variance

We measured the physiological and biochemical responses of preterm lambs to intra-amniotic injection of interleukin-1α (IL-1α). Singleton lamb fetuses at 126 days of gestation were randomized to receive 125 μg IL-1α or vehicle control via ultrasound-guided intra-amniotic injection. Each lamb was delivered 48 h later by cesarian section and ventilated for 120 min. Relative to controls, IL-1α-treated lambs had higher dynamic compliance, ventilatory efficiency indices, and saturated phosphatidylcholine levels (all p < 0.05). Umbilical cord plasma cortisol and catecholamine levels, white blood cells and differentials, cardiac output, regional blood flow, and kidney function did not differ between the groups. However, at 120 min after delivery, the cortisol levels for IL-1α-treated animal were higher than for controls. Single intra-amniotic IL-1α treatment increases surfactant pool size and improves dynamic compliance in the absence of an inflammatory response or differences in other indicators of fetal or newborn organ function.

1) fetal betamethasone injection 48 h before delivery stabilizes GFR and significantly alters endocrine function in preterm newborn lambs, and 2) the addition of T4 does not augment betamethasone-induced renal and endocrine responses.