Kari S. Kretch

Aims: Our primary aim was to determine the immediate effects of using a supported stepping device on the real-time locomotor behavior of pre-walking infants with Down syndrome (DS). Our secondary aim was to characterize the role of the caregiver in facilitating infant locomotor behavior by quantifying infant-initiated and caregiver-initiated walker movement, and to test whether walker movement encourages stepping behavior. Methods: Pre-walking infants with DS played with their caregiver in two conditions—with and without assistance from a wheeled suspension walker. To examine changes across development, we recorded infants across one to four sessions from 10 to 19 months of age. Results: Across developmental stages, we found that suspension walkers robustly increased infants’ locomotor behavior: The walker increased upright time, percent time stepping, stepping rate, upright bout rate, percent time locomoting, and total bout rate. Most walker movement was initiated by caregivers, and infants stepped more while the walker was moving compared to stationary. Conclusions: Even without practice, pre-walking infants with DS were able to take advantage of the suspension walker to increase their locomotor behavior. Caregivers facilitated infants’ activity by moving the walker. Future work will examine the potential of overground suspension walkers for home-based intervention.

Infants learn through everyday interactions with the physical and social environment. For infants with cerebral palsy (CP), motor impairments may disrupt everyday learning opportunities. How can we measure real-world motor behavior and learning opportunities in infants with CP? Machine learning models have been developed to quantify body position throughout a day in infants with typical development (TD) using wearable sensor data. However, these models have not been validated in infants with motor impairments. This study assessed the validity of body position classification using machine learning and sensors in infants with CP. Ten infants with CP (7-18 months; one session each) and 19 infants with TD (4-12 months; 45 sessions) wore four inertial sensors on their legs throughout a day. Ninety minutes were video recorded and manually scored for body position in five categories: supine, prone, sitting, standing, and held. Random forest classifiers were trained to predict body position from sensor-derived motion features. Models trained on datasets that varied in size (9, 45, or 54 sessions) and group composition (CP, TD, or CP and TD) were compared to determine the most accurate model for infants with CP. Larger training sets and training sets that included data from infants with CP were the most accurate; the final models achieved similar performance in CP and TD (86%/89% accuracy), captured meaningful individual differences (ICCs = 0.682-0.999), and generated predictions that were correlated with motor skill assessments. Findings demonstrate that wearable sensors and machine learning can accurately classify real-world body position in infants with CP.

Importance: Children with Down syndrome (DS), a genetic condition associated with neuromotor impairments, walk ∼1 year later than typically developing peers. Treadmill training is the most successful known intervention for accelerating walking onset in DS. Overground stepping with mobility devices better mimics critical properties of real-world walking, but it is unknown how overground stepping develops in pre-walking infants with DS. Objective: We aimed to characterize the developmental trajectory of stepping quantity and quality in supported overground stepping compared to supported treadmill stepping. We also measured infants’ ability to self-propel in the walker. Finally, we assessed caregivers’ perspectives on both devices. Design: We tested infants at 10, 13, 16, and/or 19 months of age. Setting: This study occurred in a university laboratory in the United States. Participants: We tested 31 pre-walking infants with Down syndrome across 69 sessions. Exposure: At each session, infants completed four trials per task (treadmill and walker) and a test of self-propulsion in the walker. Main Outcomes and Measures: We measured step quantity (overall step rate and alternating step rate), step quality (percentage of steps that were alternating, forward, and flat-landing), the ability to self-propel the walker, and caregiver perspectives on both devices. Results: Step quantity increased with age and varied by task—infants took more steps per minute in the walker compared to the treadmill. Moreover, steps were of equal or higher quality in the walker. By 16 months, about half of infants could self-propel. Caregivers viewed both devices favorably, though the majority preferred the walker for home and/or community use. Conclusions: Overground walkers promote more stepping than a treadmill in pre-walking infants with DS, with stepping of similar or higher quality. Caregivers feel positively about overground walkers. Relevance: Overground stepping using a suspension walker shows promise as an intervention for pre-walking infants with Down syndrome.

Positioning—the body's physical configuration and relations to supports and restraints—is a fundamental aspect of infants' everyday experiences. How do everyday positioning experiences (the amount of time spent in different positions during daily life) change with the acquisition of postural skills like sitting? This study investigated relations between sitting status (whether infants have achieved a sitting milestone), sitting age (amount of time before or after that milestone), and everyday positioning experience. Forty‐three infants participated at 4, 5, 6, and/or 7 months of chronological age. Everyday experience was measured using Ecological Momentary Assessment: Caregivers reported infants' current position repeatedly throughout their daily activities. The best predictors of everyday sitting experience (proportion of responses in which the infant was in an unrestrained sitting position) were chronological age and overall sitting age, calculated from the first day infants sat using hands for support; hands‐free sitting age, calculated from the first day infants sat without hands, did not uniquely contribute. Sitting experience supplanted supine experience, which decreased with overall sitting age; the effect of overall sitting age on prone experience varied with chronological age. Time restrained by an adult decreased only with chronological age, and time restrained by a device was not related to chronological or sitting age. Results suggest that the continuous development of sitting skill changes the positioning composition of infants' everyday unrestrained floor time.

Infant-parent coordination during play is an important facilitator of the development of language, attention, and social cognition. Although the dynamics of triadic interaction in the second year of life are well documented, less is known about how infants and parents coordinate attention earlier in development. Prior work has shown that pre-sitting infants often play facing away from their parents, making visual access to faces difficult. However, it is not yet known whether and how this might affect their ability to coordinate attention to objects. Twenty 5- to 7-month-old infants (10 sitters, 10 nonsitters; 11 girls; nine Hispanic/Latino) were observed while they played with a parent in two conditions: sitting on the floor and sitting in a supportive infant seat. Infants and parents wore head-mounted eye trackers to record their visual attention, and their manual actions were coded from video. In the seat, parents always placed their infants facing toward them, but when sitting on the floor, parents frequently placed their infants facing away to provide manual support from behind. Surprisingly, coordination of attention was not disrupted, but facilitated, when infants faced away from their parents. This was likely due to greater rates of hand-eye coordination for both infants and parents while facing away, which strengthened the validity of the "hand-following" pathway to coordinated attention. Therefore, infants and parents can maintain high degrees of coordination during play without being able to see each other's faces. This phenomenon may have implications for developmental trends in infant attention throughout the first year of life. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

The development of independent sitting is associated with language development, but the learning experiences underlying this relationship are not well understood. Additionally, it is unknown how these processes play out in infants with motor impairments and delays in sitting development. We examined the real-time associations between sitting and caregiver speech input in 28 5–7-month-old infants with typical development and 22 7–16-month-old infants with cerebral palsy who were at a similar stage of early sitting development. We hypothesized that object labels would be more likely to co-occur with moments of optimal attention to the labeled object while sitting than while in other positions. Infants were video recorded in five minutes of free play with a caregiver. Coders transcribed caregivers’ speech, identified instances of object labeling, and coded infants’ and caregivers’ attentional states during object labeling episodes. We found that caregivers labeled more objects while infants were sitting than while they were in other positions. However, object labels were not more likely to co-occur with infant attention, infant multimodal attention, or coordinated visual attention to the labeled object during sitting. Infants with cerebral palsy were exposed to fewer labels and were less likely to be attending to objects as they were labeled than infants with typical development. Our findings shed light on a possible pathway connecting sitting and language in typical and atypical development.

Background/Objectives: The Early Identification and Intervention for Infants (Ei3) Network is an interdisciplinary team dedicated to improving early detection and intervention of cerebral palsy (CP) in California. This paper describes the key (1) awareness-building and (2) capacity-building strategies utilized by the Ei3 Network in the first two years. Methods: Awareness-building methods included interactive conference discussions, resource deliverable creation, and the creation of a framework for dissemination. Capacity-building methods were hosting assessment training, gathering stakeholder feedback, and implementation training. All deliverables were created with a minimum of 3 review and revision cycles. We planned, hosted, and provided scholarships for training, including the Hammersmith Infant Neurological Examination (HINE), Prechtl’s GMA, and an implementation conference. Preliminary descriptive statistics and paired samples t-tests were performed on HINE training surveys. Results: Seven resource deliverables were created and distributed. A professional website, @steps2home.org, was launched. Online channels gained followers (146, Instagram; 198, X; 298, Mailchimp). Providers participated in various trainings: the Sykes Symposium on early detection and intervention (70), HINE (211), GMA Basic or Advanced (46), and Implementation Conference (six facilities from April 2023 to June 2024). HINE training participants reported increased ability to identify CP (p = 0.001), knowledge of (p = 0.004) early detection, ability to implement early detection guidelines (p < 0.001), and confidence in performing the HINE on the post-test (79.87%). Conclusions: The first two years of Ei3 resulted in increased awareness of the early detection guidelines through resources to help providers and families navigate complex care systems and dissemination through online and in-person strategies. We built capacity by training an increased number of providers to identify infants at risk of CP and implement the early detection guidelines. Engagement of stakeholders in focus groups, reviewing documents, and including a parent panel throughout the process increased the value of this work and should support the expansion of the network in the next year.

Purpose: To characterize beliefs of pediatric physical therapists (PTs) in the United States regarding the role of crawling in infant development and clinical practice. Methods: Pediatric PTs reported their beliefs about early mobility and crawling, clinical approaches related to early mobility and crawling, and agreement with the removal of crawling from the Centers for Disease Control and Prevention (CDC)'s updated developmental milestone checklists in an online survey. Analyses examined associations between information sources and beliefs, between beliefs and clinical approaches, and between beliefs and CDC update opinions. Results: Most participants believed that crawling was important (92%) and linked to a variety of positive developmental outcomes (71%-99%) and disagreed with its removal from the CDC checklists (79%). Beliefs were linked with clinical approaches focused on promoting crawling and discouraging other forms of mobility. Conclusions: Further research is needed to determine whether pediatric PTs' beliefs and clinical practices are supported by evidence.