Development of Movement and Postural Patterns in Full-Term Infants Who Are at Low Risk in Belgium, India, Norway, and the United States.

Objective: The objective of this study was to investigate the influences on motor development in infants who are at low risk from Belgium, India, Norway, and the United States using the General Movement Assessment at 10-16 weeks postterm age.

Methods: This was a cross-sectional study of prospectively enrolled full-term infants at low risk (n = 186). Certified General Movement Assessment observers rated the fidgety movements, quality of the movement patterns, age-adequacy of the movement repertoire, postural patterns, movement character, and overall Motor Optimality Score-Revised (MOS-R). Scores were evaluated for associations with sex, birth weight category, gestational age, postterm age at video, and country.

Results: The majority of infants had normal fidgety movements (179/186, 96.2%). This did not vary by sex, birth weight, gestational age, postterm age at video, or country. All infants showed normal>atypical movement patterns. Variability was seen for age adequacy (optimal: 137/183, 74.9%), postural patterns (normal>atypical: 164/183, 89.6%), and smooth/ fluent movement character (138/183, 75.4%). Gestational age and postterm age at video were associated with atypical postural patterns, but in multivariable regression, only younger postterm age retained significance (OR = 2.94, 95% CI = 1.05-8.24). Lack of age adequacy was associated with postterm age (OR = 13.15, 95% CI = 4.36-39.72) and country (compared with Norway; Belgium OR = 3.38 95% CI = 12.4-9.22; India OR = 3.16, 95% CI = 1.01-9.87; United States not significant). Infants from India also showed lower rates of an optimal MOS-R (25-28) than infants from Norway.

Conclusion: The normality and temporal organization of fidgety movements did not differ by sex, birth weight, postterm age, or country, suggesting that the fidgety movements are free of cultural and environmental influences. The majority of full-term infants who were healthy in this cohort showed normal scores for all aspects of motor development tested using the MOS-R. Differences in age adequacy and MOS-R by country warrant investigation with larger cohorts and longitudinal follow-up.

Impact: Understanding variations in typical motor development is essential to interpreting patterns of movement and posture in infants at risk for atypical development. Using the framework of Prechtl's General Movement Assessment, this study showed that the development of movement and posture in healthy infants was affected by age and country of birth, but the development of the fidgety movements appeared to be free of these influences. Local norms may be needed to interpret the Motor Optimality Score-Revised in all populations, but further research on this topic is needed.