Background and Objectives: Early postnatal steroid administration is a strategy to prevent bronchopulmonary dysplasia (BPD) in extremely preterm-born infants. The effect of low dose, early, postnatal hydrocortisone on brain white matter is unknown. This study assessed variation in connectivity metrics of major white matter pathways in the cerebrum and cerebellum at near-term gestational age among infants who did or did not receive a standardized regimen of hydrocortisone during the first 10 days of life. Methods: Retrospective cohort study. Participants: Infants born < 28 weeks gestation, divided into 2 groups based on steroid protocol: Protocol group had 50%-150% of the protocol, 0.5mg/kg hydrocortisone twice daily for 7 days, followed by 0.5 mg/kg per day for 3 days (n=33) versus Non-Protocol, (0 to less than 50% protocol dose, n=22). Infants had near-term diffusion MRI (dMRI) as part of the clinical imaging protocol. We assessed group differences in dMRI mean fractional anisotropy (FA) and mean diffusivity (MD) across the corticospinal tract, inferior longitudinal fasciculus, anterior, middle, and posterior corpus callosum and superior cerebellar peduncle. Results: The groups were well matched on gestational age, post-menstrual age at scan, total number of medical complications, incidence of BPD (i.e., needing O2 at 36 weeks), and incidence of necrotizing enterocolitis. No significant group differences were identified in mean FA or MD in any cerebral or cerebellar tract between the two groups. Conclusion(s): Low dose, early, postnatal hydrocortisone was not associated with significant differences in white matter tract microstructure at near term gestational age.

The authors have declared no competing interest.

All phases of this study were supported by the Society for Developmental Behavioral Pediatrics Research Grant to Sarah E. Dubner, and by the National Institutes of Health- Eunice Kennedy Shriver National Institute of Child Health and Human Development (K.E. Travis, PI; 5R00HD8474904; H.M. Feldman, PI; 2RO1- HD069150).

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The Institutional Review Board of Stanford University gave ethical approval for this work #IRB-44480.

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