Neurodevelopmental trajectories from birth to childhood and their impairments: insights from passive, spontaneous, and locomotor-like movements.

Human motor behaviour emerges from the dynamic interplay between the developing nervous system and the musculoskeletal apparatus, progressing from spontaneous fetal movements to postural control and early locomotion, including interpersonal coordination. Careful analyses of these behaviours may provide insight into the functional integrity of spinal and supraspinal networks, and early detection of abnormalities in high-risk populations such as preterm infants. This review summarizes our knowledge on neuromotor development from birth to early childhood, highlighting how passive, spontaneous, and locomotor-like behaviours reflect the maturation of sensorimotor circuits. We describe the transition from prenatal activity to postnatal movements, and the gradual emergence of coordinated postural and locomotor patterns. Special attention is given to the limitations of observational tools and the growing role of quantitative kinematic, kinetic and electromyographic (EMG) techniques, which enable objective assessment of motor variability, interlimb coordination, neuromuscular activation, primitive locomotor patterns, and interpersonal coordination. By integrating the findings from a rich motor repertoire, such as the assessment of General Movements, with quantitative neurophysiological findings, deviations from typical behaviour can reveal early dysfunction of sensorimotor pathways, and predict later motor impairments such as Cerebral Palsy. Combining these perspectives moves toward more accurate and timely identification of infants at risk, ultimately supporting earlier, individualized intervention strategies.