Preterm and early postterm motor behaviour in low-risk premature infants.

The development of spontaneous motility and posture was studied longitudinally in 14 carefully selected low-risk preterm infants. The aim of this investigation was to provide a set of data suitable for comparison with fetuses and with neurologically abnormal preterm infants. The infants were videorecorded weekly, for one hour in a supine position, from birth until their discharge from the hospital. Ten of them were thereafter also observed at home at 3-week intervals from 3 to 18 weeks of corrected age, together with 10 healthy fullterm infants. Occurrence and duration of motor patterns and postures in periods of rest and activity were obtained by off-line analysis of the videotapes. Few significant changes were found from birth until term age in the composition and quantity of the spontaneous movement patterns. Only twitches and stretches during activity periods showed a small decline approaching term age. However, notable inter-individual differences and intra-individual fluctuations from week to week were observed. Postterm development of preterm infants was similar to that of the fullterms. Both showed considerable changes in the qualities of general movements after the first postterm weeks. Only fidgety character movements occur earlier in preterm infants. No age-specific preference postures of the limbs were found in the preterm period. Midline position of the head in supine was observed at about the same postterm age in preterm and fullterm groups. Asymmetrical tonic neck postures were very inconsistently present before term age and rapidly disappeared after term, earlier so in preterm infants.