Late preterm (LP) birth, defined as delivery at 34–36 weeks of gestation, occurs during a period of rapid brain development. White matter expands substantially, while synapse formation, dendritic growth, cortical folding, and brain surface expansion continue. Previous studies have reported mixed findings, leaving the long-term effects of being born several weeks early unclear.
Addressing this challenge, a research team was led by Specially Appointed Professor Akemi Tomoda from the Research Center for Child Mental Development at the University of Fukui, Japan, alongside doctoral student Ryoko Yoshinare, Assistant Professor Masatoshi Yamashita, and Professor Yoshifumi Mizuno from the same institution. Using data from the U.S.-based Adolescent Brain Cognitive Development (ABCD) Study, the researchers compared 1,093 LP birth children with 8,984 full-term (FT) birth children aged 9–11 years. They examined behavioral and emotional problems, cognitive function, structural magnetic resonance imaging (MRI), diffusion tensor imaging (DTI), and resting-state functional MRI. Their findings were published on July 20, 2026, in Volume 14 of the journal Frontiers in Pediatrics .
The longitudinal analysis found no broad LP–FT differences in behavioral and emotional problems, most cognitive outcomes, cortical thickness, cortical surface area, or resting-state functional connectivity. Structural MRI identified group differences in six regional brain volumes: the left postcentral, right fusiform, right middle temporal, right pars orbitalis, right supramarginal, and right insular regions. However, these measures showed no significant timepoint or group-by-timepoint effects after false discovery rate correction.
The clearest differences emerged from DTI, which assesses diffusion properties of brain tissue. Group effects were identified in selected white matter, cortical, and subcortical fractional anisotropy (FA) and mean diffusivity (MD) measures. The inferior longitudinal fasciculus showed group effects for FA and MD, although in different hemispheres. Group-by-timepoint interactions were also detected across several white matter tracts and selected cortical and subcortical regions. Analyses suggested that many interactions reflected decreases in DTI measures among FT children over 2 years, whereas LP changes were smaller, nonsignificant, or less consistent.
“These findings suggest that the effects of LP birth may be subtle and may not necessarily appear as broad behavioral or cognitive difficulties,” said Prof. Tomoda. “Instead, brain imaging may reveal regional differences in maturation that are not immediately evident in everyday functioning.”
The absence of widespread behavioral or cognitive differences is reassuring, while the DTI results suggest that selected aspects of brain microstructural development may follow different patterns. Because FA and MD are influenced by multiple tissue properties, the results do not establish a specific mechanism such as altered myelination or axonal organization. The imaging differences do not establish that every LP child will develop difficulties or that these differences cause functional problems.
“LP birth should not be viewed as a prediction of poor developmental outcomes,” Prof. Tomoda added. “Rather, our results support continued awareness of individual developmental needs, so that children who experience emerging difficulties can receive appropriate assessment and support.”
Overall, the study indicates that LP birth is associated with selected regional brain-volume and DTI differences during early adolescence, with longitudinal differences particularly evident in DTI measures. The researchers emphasize that substantial follow-up attrition, only two assessment timepoints, retrospective gestational-age reporting, and the observational design limit interpretation. Further longitudinal research is needed to determine whether these subtle neuroimaging differences persist, change, or relate to later cognitive, behavioral, or educational outcomes.
Reference
Title of original paper: Neurodevelopment and brain maturation in late preterm children: insights from the adolescent brain cognitive development (ABCD) study
Journal: Frontiers in Pediatrics
DOI: https://doi.org/10.3389/fped.2026.1827902
About University of Fukui, Japan
The University of Fukui is a preeminent research institution with robust undergraduate and graduate schools focusing on education, medical and science, engineering, and global and community studies. The university conducts cutting-edge research and strives to nurture human resources capable of contributing to society on the local, national, and global level.
Website: https://www.u-fukui.ac.jp/eng/
About Professor Akemi Tomoda from University of Fukui, Japan
Prof. Akemi Tomoda is a Special Appointment Professor and Head of Department at the Research Center for Child Mental Development, University of Fukui, Japan. Specializing in multidisciplinary brain research and child development, she has authored 255 scientific publications, earning over 7,000 citations. Her extensive expertise spans the neurobiology of young adults, chronic fatigue syndrome, circadian rhythms, and melatonin. As a leading authority in sleep disorders and sleep medicine, her pioneering work significantly advances our understanding of pediatric mental health. Through rigorous longitudinal studies, her landmark research successfully bridges clinical neurology, childhood development, and public health strategies worldwide.
Funding information
The author(s) declared that financial support was received for this work and/or its publication. This study was supported by JSPS KAKENHI Scientific Research (C) (24K05854, RY, MY, YM, AT), a research grant from the Strategic Budget to Realize University Missions (AT, YM), a Grant-in-Aid for Translational Research from the Life Science Innovation Center, University of Fukui (AT), and Life Cycle Medicine from the Faculty of Medical Science, University of Fukui (RY). The ABCD Study is supported by the National Institutes of Health and additional federal partners under award numbers U01DA041048, U01DA050989, U01DA051016, U01DA041022, U01DA051018, U01DA051037, U01DA050987, U01DA041174, U01DA041106, U01DA041117, U01DA041028, U01DA041134, U01DA050988, U01DA051039, U01DA041156, U01DA041025, U01DA041120, U01DA051038, U01DA041148, U01DA041093, U01DA041089, U24DA041123, and U24DA041147.
Frontiers in Pediatrics
Observational study
People
Neurodevelopment and brain maturation in late preterm children: insights from the adolescent brain cognitive development (ABCD) study
20-Jul-2026
The author(s) declared that this work was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.