The effects of repeated antenatal glucocorticoid therapy on the developingbrain

Antenatal glucocorticoid (GC) therapy improves infant outcome following pre term birth. As approximately 50% of women given a first course of antenatal GCs remain undelivered 7-14 d later, many clinicians administer further co urses. GCs are known to be neurotoxic and there is concern that exposure du ring early development may have adverse effects on the immature brain. The aim of this investigation was to compare magnetic resonance (MR) indices of brain maturation in infants exposed to repeated antenatal GC therapy and b orn at or close to term, with non-GC exposed control infants. MR images wer e obtained during quiet sleep without sedation. TI weighted volume images w ere obtained in the sagittal plane and T1, T2 weighted spin echo and invers ion recovery images in the transverse plane. Brain volume and surface area were calculated from segmented image slices, and a measure of the complexit y of cortical folding, the whole cortex convolution index (WCCI), from comp uterized analysis of a vector coded contour following algorithm. Analysis o f covariance was used to compare the two groups after allowing for the effe ct of postmenstrual age. There were 10 infants in the GC group (range of an tenatal GC exposure, 3-11 courses) and 6 controls. Each GC course comprised two 12-mg IM doses of betamethasone 24 h apart. GC exposed infants had a s ignificantly lower WCCI (p = 0.001) and smaller surface area (p = 0.02), af ter allowing for postmenstrual age. There was no significant difference in brain volume (p = 0.5). Repeated antenatal GC exposure results in measurabl e differences in brain maturation when compared with gestational age matche d non-GC exposed controls. The clinical relevance of these observations is not known.