Trajectories of serial motor scores of typically developing children: Implications for clinical decision making.

This longitudinal study generated predicted fine motor (FM) and gross motor (GM) percentile score trajectories for typically developing children during infant and preschool years and compared the trajectories. Data from the same 83 children at 9 assessment points between 9 and 21 months and 4 to 5(1/2) years were used in multi-level models. Non-linear equations provided the best fit for predicting percentile rank scores over time for the infant data. For preschool data, the best fit for GM data remained non-linear while the FM data was best represented by a linear equation. Within-subject variability decreased in the preschool years. On average, girls had higher FM scores than boys in both age ranges. The results support the concept of developmental surveillance rather than single point assessments. Health care providers who practice developmental surveillance need to be aware that fluctuations in scoring patterns can be expected in typical development.