The human brain undergoes rapid transformations before and immediately after birth. A major new study shows that differences in brain development in girls and boys appear earlier than previously thought, as early as the second half of pregnancy.
For the first time, researchers at the University of Cambridge have been able to follow the development of the human brain from mid-pregnancy to the first month of life, using images obtained both prenatally and postnatally. The analysis shows that sex-related differences in the rate of brain growth are already visible before birth.
Until now, most studies have focused either on the intrauterine period or on newborns and infants, leaving the transition between intrauterine and extrauterine life underexplored. The lack of a continuous perspective made it difficult to establish the exact moment in which these differences appear and how they subsequently evolve, according to News.ro.
The team from the Center for Autism Research at the University of Cambridge approached early brain development as a continuous process, analyzing nearly 800 prenatal and postnatal scans from the Developing Human Connectome Project, one of the largest imaging databases dedicated to the perinatal period.
The results, published in the journal Scientific Reports, indicate that there are prenatal differences in the way the brain grows by sex. On average, the male brain shows a greater increase in total volume compared to the female, with differences being observed at the level of the entire brain.
The research also provides detailed information on the different maturation rates of brain components. In mid-pregnancy, the white matter – responsible for connecting different regions of the brain – contributes the most to the increase in brain volume. Towards the end of pregnancy and after birth, the gray matter, involved in cognitive processes, becomes dominant.
Also, subcortical gray matter structures such as the amygdala, cerebellum, and thalamus reach peak growth rates earlier than cortical gray matter. This suggests that basic brain functions mature before those involved in complex cognitive processes.
The authors point out that early identification of these trajectories of brain development is essential for understanding how differences arising from intrauterine life can influence later development. These findings could have important implications for the study of neurodevelopmental disorders and psychiatric conditions, such as autism, associated with differences in the rate of brain growth.
