Gross motor development of Thai healthy full-term infants aged from birth to 14 months using the Alberta Infant Motor Scale: Inter individual variability

Background: The gross motor percentiles of the Alberta Infants Motor Scale (AIMS) have been commonly referenced in research. Cross-cultural assessment of gross motor development during the first year of life is suggested as diverse child-rearing practices can cause inter-variability. The main aim of this study was to develop an AIMS percentile curve for typically developing home-raised infants in the northeastern part of Thailand. The AIMS scores of these infants were also compared with the standard Canadian norms. Methods: The gross motor development of 574 full-term infants aged 15 days to 14 months was assessed using the Thai version of the AIMS. Percentile curves of their gross motor ability were developed. The Thai infants' mean AIMS scores were compared with the Canadian norm using the one-sample t-test. Results: The percentile curve of gross motor development of healthy Thai infants showed that mean AIMS scores increased with age. Large inter-variability was present from the 7th to 10th months. The mean AIMS scores of Thai infants were significantly lower than the standard Canadian means during the first three months (P < 0.05), but significantly higher in three age groups: 7-<8 months, 11-<12 months, and 13-14 months. Conclusion: The developed percentile curve of gross motor development is applicable for infants from the same demographic and environmental context. According to the study, infants from diverse cultures display a natural inter-variability in gross motor development between the 7th and 10th months.