PMAPostmenstrual age AIM The aim of this study was to investigate the relationship between the characteristics of spontaneous movements in preterm infants at term age and developmental delay at 3 years of age.METHOD We analysed video recordings of the spontaneous movements in the supine position of 124 preterm infants (44 males, 80 females) at 36 to 44 weeks postmenstrual age (PMA). The infants were born preterm (22-36wks PMA; birthweight 489-1696g) and had not received a diagnosis of a neurological or developmental disorder by the age of 3 years. The recorded spontaneous movements were quantified using six movement indices, which were calculated from two-dimensional trajectories of all limbs. The infants were divided into three developmental groups, normal, borderline, or delayed, based on their developmental quotient as calculated using the Kyoto Scale of Psychological Development 2001 (Kyoto Scale) at 3 years of age. Group differences in the movement indices were analysed. RESULTSIn the delayed group, average velocity of arms and legs were significantly lower (p<0.05 and p<0.01 respectively), the numbers of movement units of arms and legs were significantly lower (p<0.05 and p<0.01 respectively), kurtosis of acceleration of arms and legs was significantly higher (p<0.05 in each case), and correlation between limb velocities was higher (p<0.05) than in the normal group.

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We examined the characteristics of spontaneous movements at 9-20 weeks postterm age in very low birth-weight infants who later developed autism spectrum disorder (ASD). We analyzed video recordings of spontaneous movements of 39 children who had no clinical issues [typically developing (TD) group], 21 children who showed developmental delay, and 14 children who were diagnosed with ASD (ASD group) at 6 years of age. Head position in each video frame was classified by visual inspection. The percentage of midline head position (PMHP) and number of changes in head position were calculated. Spontaneous limb movements were quantified using six indices. The values of PMHP were significantly lower in the ASD group than in the TD group. The lower PMHP during early infancy is associated with later development of ASD. Poorer performance in maintaining midline position of the head at this period may distinguish infants who later develop ASD from those who show TD.

Abstract. [Purpose] In this study, we quantitatively evaluated how the positioning program influenced the movement patterns of preterm infants in the neonatal intensive care unit (NICU). [Subjects and Methods] Spontaneous movements of 12 low-risk preterm infants were video-recorded at 38 or 39 postmenstrual weeks of age (PMA). Six of them (positioning group) received a positioning program from birth to 35-36 weeks of PMA while the other 6 (non-positioning group) did not. We attached reflective markers on the infant's wrists and ankles in the supine position and filmed them from above. By using a two-dimensional image analysis system, we digitized the wrist and ankle trajectories and analyzed the data by calculating several statistics.[Results] Infants in the positioning group brought their hands to the midline or crossed their hands over the midline and showed more variation in velocity of movements than those in the nonpositioning group. We also noticed that infants in the positioning group exhibited and maintained a movement pattern similar to that of full-term infants at 1 month after the positioning program was terminated.[Conclusions] These results suggest that appropriate positioning of preterm infants facilitates flexion posture and movement patterns toward the centre of the body similar to foetuses in the uterus.

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