From Fetal to Neonatal: Divergent Trajectories of Human Brain Iron Development Across Regions Revealed by Whole-Brain R2* Assessment

Motivation: Sufficient iron is critical for early brain development, but the timing and sequence of brain iron changes from fetal to neonatal stages remain unclear. Goal(s): We aim to map brain iron growth trajectories across birth and examine how sex, age at birth, and birth weight influence R2* development Approach: Using a longitudinal multi-echo fMRI dataset, we estimated R2* in 88 regions and modeled growth from 25 to 55 post-conceptual weeks. Results: Most parietal regions show near-linear trajectories, while occipital regions exhibit non-linear trends, with faster increases before birth. Certain regions in the frontal lobe and temporal lobe develop faster after birth. Impact: These findings provide the first insights into R2* development across birth longitudinally, laying the foundation for future research into the neural mechanisms underlying iron deficiency-related developmental disturbances.