Monitoring a baby’s gross motor development is a concern for parents and healthcare providers during the first year and a half of life. Standardized tools are used by pediatric professionals to evaluate how an infant is acquiring movement skills compared to other children their age. These assessments help identify infants who may benefit from extra support or early intervention services. The Alberta Infant Motor Scale (AIMS) is a reliable tool used to track developmental progress and determine if a child’s gross motor skills are progressing typically. Understanding the results of this assessment is important for knowing when a child is on a typical trajectory.
Defining the Alberta Infant Motor Scale (AIMS)
The Alberta Infant Motor Scale (AIMS) is a standardized, norm-referenced assessment tool designed to evaluate the gross motor maturation of infants. Gross motor skills involve the large muscles of the body, used for activities like sitting, standing, and walking. Developed by Canadian researchers, the AIMS evaluates children from full-term birth up to 18 months of age, or until they begin walking independently.
The primary purpose of this scale is to track and identify motor delays by comparing an infant’s performance to established age-related norms. This assessment helps determine if a child is acquiring motor skills at an expected pace, making the AIMS a valuable screening instrument in pediatric clinics.
Understanding AIMS Scoring and Percentiles
The AIMS assessment results are initially calculated as a raw score, which counts the motor skills observed. This raw score is converted into a percentile rank, which is the most meaningful result for understanding the infant’s performance. The percentile rank compares the child’s score to the scores of thousands of other children in the normative sample who are exactly the same age.
A “positive score” is best understood by looking at the percentile rank, where a typical result is considered a positive outcome. A child scoring in the 50th percentile, for example, means they scored better than 50% of their peers. A score indicating typical development generally falls above the 25th percentile, suggesting the child’s motor skills align with the majority of their age-matched peers.
The threshold for identifying a significant delay is conventionally set at the 5th percentile. A child whose score falls at or below the 5th percentile is considered “at-risk” for a motor delay. This indicates that their motor skill development is substantially slower than 95% of infants their age. Therefore, a “positive score” signifies a percentile rank above the 5th percentile, confirming a typical motor skill acquisition pattern. Scores between the 5th and 25th percentile are often interpreted as a mild to moderate delay and may warrant closer monitoring.
How the AIMS Assessment is Performed
The AIMS assessment is a purely observational tool; the examiner does not physically guide the infant through movements. The procedure typically lasts 20 to 30 minutes and relies on the trained professional watching the infant’s spontaneous activity. The environment is arranged to encourage the baby to move naturally, often by placing toys just out of reach.
The scale is structured around 58 specific items, divided into four sub-scales based on the infant’s position during observation. These four positions are prone (lying on the tummy), supine (lying on the back), sitting, and standing. The examiner observes the quality and quantity of the infant’s movements, noting which motor skills are consistently demonstrated. For each position, the professional records the least and most advanced skill the infant has mastered, which helps track the progression of motor achievement. This observational approach focuses on how efficiently the child moves, not just whether they achieve a milestone. The total number of observed skills forms the raw score, which is then used to find the percentile rank.
Interpreting Scores and Recommended Follow-up
Once the percentile rank is determined, the score guides clinical decisions regarding the need for monitoring or intervention. A score consistently above the 5th percentile suggests the child is developing motor skills typically, and no specialized intervention is usually recommended. These children are monitored through routine well-child visits to ensure continued progress.
For an infant whose score falls at or below the 5th percentile, the recommendation is typically for close follow-up and a referral to early intervention services. Although the AIMS is a sensitive screening tool, it does not provide a medical diagnosis for the underlying cause of the delay. The low score acts as a red flag, indicating that timely intervention, such as physical therapy, is warranted to optimize developmental outcomes. Early intervention is beneficial because the infant brain is most adaptable during this period of rapid development. A lower score simply signals a need for action, allowing professionals to address potential motor issues as early as possible.