Comparison of leg movements in preterm infants at term with healthy full-term infants.

This study describes the differences and similarities in movement of low-risk preterm and full-term infants of comparable postgestational ages using a sensitive and quantitative measurement system, kinematic analysis. Subjects were 25 low-risk infants, 10 born at 34 to 36 weeks gestational age and 15 at term. Spontaneous leg movements were videotaped, and a 10-second segment was digitized to provide kinematic data. Data obtained were compared to evaluate the neurological maturation of preterm infants and to investigate the influence of the extrauterine environment on movement. Results showed that all infants had organized movement as determined by high interjoint correlations, small phase lags, and constrained movement durations. Pause durations and joint angles differed among infants. Infant leg movements are highly organized synergies and are not influenced by extrauterine environmental events. Differences in movements are attributed to dynamic interaction of elements in the motor control system. Additional studies with full-term infants may provide further insight into the constraints and supports of the immediate environment on movement outcome.