The onset of rhythmic activities in normal and high-risk infants.

The onset of rhythmic activities was compared for 2 groups of high-risk infants (a preterm Respiratory Distress Syndrome and a postterm postmature group) and a normal term group over their 1st year of life. The postterm postmature group experienced earlier onsets of rhythmic activities. The preterm RDS group showed delays in the onset of rhythmic activities, but when a correction was made for the prematurity, did not differ from the other groups. These differences suggest that the onset dates for rhythmic activities are not affected by the perinatal complications of RDS or postmaturity, but are related to gestational age differences. A comparison of the 3 groups on Bayley 1st-year motor skills revealed group differences even after an adjustment for gestational age differences, suggesting that the development of motor skills, unlike the development of rhythmic activities, may have been affected by these perinatal complications.