Spontaneous movements in the first four months of life: An accelerometric study in moderate and late preterm infants

Background: Moderate preterm infants (MPI) and late preterm infants (LPI) account for the majority of children born preterm. Up to 5% of MPI and LPI are estimated to manifest neurodevelopmental impairments. However, information about normal early motor development in these patients is lacking. Aim: To find characteristic patterns for motor development in the first four months of life among MPI and LPI without risk factors for developmental impairment by using accelerometry of spontaneous movements. Study design: Prospective and observational study. Subjects: Twenty-three MPI and LPI (9 female, 14 male) without known risk factors for neurodevelopmental impairment were included in this study. Spontaneous movements were measured by accelerometry at the time of hospital discharge (mean: 36.6wks postmenstrual age (PMA)) and at the corrected age of three months (mean: 53.0wks PMA). Outcome measures: Motor development was described by analyzing 36 parameters calculated from the acceleration signal. Normal neurodevelopmental outcome was confirmed by Bayley Scales of Infant Development at the corrected age of two years. Results: Statistically significant differences (p < 0.05) between the two measurements could be shown in 26 out of the 36 parameters. Striking changes in motor development were an increase in acceleration and variability of the spontaneous movements, the main criterion for analyzing spontaneous movements. Furthermore, the regularity of spontaneous movements increased significantly. Conclusion: Characteristic patterns of normal motor development in MPI and LPI can be identified and provide a basis for future investigations aiming at the early detection of abnormal motor development for this specific patient group.