Differential effects on fetal growth and development of repeated fetal or maternal corticosteroid treatments [ 2000 - 2002 ]

Research Grant

Researchers: Prof John Newnham (Principal investigator)

Brief description Injections of synthetic hormones (corticosteroids) to women at risk of early preterm birth reduce the rate of respiratory illness and death in the newborn infant. It is standard clinical practice prior to early preterm birth to give corticosteroids by intramuscular injection to the mother. For many women, however, preterm birth does not occur as expected and it has become common practice to give repeated courses of corticosteroids to women in whom the risk of preterm delivery recurs or continues. Using the sheep model, we have shown that repeated doses of corticosteroids, given intramuscularly to the mother, are of benefit to newborn lung function, but also reduce the rate of fetal growth and adversely affect brain development. Evidence from the Western Australian Preterm Infant Cohort Study suggests that birthweight in humans is similarly affected by repeated corticosteroids and is followed by behavioral disorders in childhood. Using sheep, we have shown that repeated injections of corticosteroids given directly to the fetus cause no reduction in birthweight although maturation is still enhanced. This finding of a differential effect of corticosteroids by different routes of administration raises several exciting opportunities and questions. First is the possibility that direct fetal treatment may be of use in humans, if current human trials show that repeated doses cause effects similar to those we have seen in sheep. Secondly, the finding challenges our current understanding of how an individual may be programmed for subsequent health or illness by prenatal events. The proposed study will attempt to explain why corticosteroids given to the mother, but not the fetus, restrict fetal growth. Our hypothesis is that these hormones, when given repeatedly to the mother, adversely affect the ability of the placenta to transfer essential nutrients to the fetus. We will test this hypothesis using pregnant sheep in which catheters have been implanted surgically.

Funding Amount $AUD 356,849.62

Funding Scheme NHMRC Project Grants

Notes Standard Project Grant