The first months of life are a critical period for brain development, laying the foundation for later motor and cognitive abilities. Infants born prematurely are particularly vulnerable during this time, as they miss important stages of brain growth that normally occur in the final weeks of pregnancy. This study set out to explore differences in brain activation during reaching and grasping movements between full-term and preterm infants. To investigate this, functional near-infrared spectroscopy (fNIRS) was used. This non-invasive method, well-suited for research with young children, measures brain activity by detecting changes in blood oxygen levels using harmless light. When a part of the brain is active, it consumes more oxygen, allowing fNIRS to map which areas are engaged during specific tasks. A total of 45 infants, aged between 3 and 9 months, participated in the study. During reaching tasks, full-term infants demonstrated clear and strong activation in brain regions associated with motor control and planning. In contrast, preterm infants exhibited reduced and more diffuse activation patterns. These findings suggest that although preterm infants may appear to move similarly to their full-term peers, their brain development could still be delayed or altered beneath the surface. Interestingly, conventional neurological assessments, such as the Hammersmith Infant Neurological Examination (HINE), did not reveal significant differences between the two groups. However, the more sensitive measurements provided by fNIRS detected subtle variations in brain function that standard tests might overlook. Identifying these early signs of developmental delay could allow for earlier and more targeted support, offering preterm infants better chances for optimal growth. The findings of this research are relevant for healthcare professionals, policymakers, researchers, and parents. They demonstrate that fNIRS could be a valuable tool for early screening of brain development, particularly in preterm infants, helping to ensure that children at risk receive the care they need as early as possible.