The effects of maternal glucocorticoid administration in growth restricted fetuses.

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Antenatal administration of glucocorticoids to pregnant women at risk of preterm delivery has been shown to enhance fetal lung maturation. However, glucocorticoids such as betamethasone have a range of potentially deleterious non-pulmonary effects, which include significant alterations in fetal cardiovascular function. This is important because intrauterine growth restricted (IUGR) fetuses constitute a significant proportion of pregnancies in Australia, are at risk of preterm delivery and are therefore likely to receive maternal betamethasone. From both human observations and animal studies, it is well documented that IUGR fetuses demonstrate a range of cardiovascular adaptations that ensure maintenance of oxygen delivery to vital organs despite reduced placental perfusion. However, in recent clinical and experimental studies we have demonstrated that administration of betamethasone to IUGR fetuses induces changes in fetal blood flow that may be detrimental to the IUGR fetus. Specifically, we believe that glucocorticoids may increase the risk of both cardivascular and cerebral damage in the growth restricted fetus. The significance of these findings and the mechanisms regulating these changes remain unclear but they have clear implications for future clinical management. This proposal represents the further development of preliminary experimental studies to examine the effects of betamethasone in the ovine IUGR fetus with future clinical care in mind.