The development of independent sitting changes everyday opportunities for learning and has cascading effects on cognitive and language development. Prior to independent sitting, infants experience the sitting position with physical support from caregivers. Why does supported sitting not provide the same input for learning that is experienced in independent sitting? This question is especially relevant for infants with gross motor delay, who require support in sitting for many months after typically developing infants sit independently. We observed infants with typical development (n = 34, ages 4–7 months) and infants with gross motor delay (n = 128, ages 7–16 months) in early stages of sitting development, and their caregivers, in a dyadic play observation. We predicted that infants who required caregiver support for sitting would spend more time facing away from the caregiver and less time contacting objects than infants who could sit independently. We also predicted that caregivers of supported sitters would spend less time contacting objects because their hands would be full supporting their infants. Our first two hypotheses were confirmed; however, caregivers spent surprisingly little time using both hands to provide support, and caregivers of supported sitters spent more time contacting objects than caregivers of independent sitters. Similar patterns were seen in the group of typically developing infants and the infants with motor delay. Our findings suggest that independent sitting and supported sitting provide qualitatively distinct experiences with different implications for social interaction and learning opportunities.Highlights: During seated free play, supported sitters spent more time facing away from their caregivers and less time handling objects than independent sitters. Caregivers who spent more time supporting infants with both hands spent less time handling objects; however, caregivers mostly supported infants with one or no hands. A continuous measure of sitting skill did not uniquely contribute to these behaviors beyond the effect of binary sitting support (supported vs. independent sitter). The pattern of results was similar for typically developing infants and infants with gross motor delay, despite differences in age.

Purpose: In early 2022, the Centers for Disease Control and Prevention (CDC) updated their developmental surveillance milestone checklists. The purpose of this article is to clarify and interpret the updates from a physical therapist perspective and to discuss implications of the new milestones for physical therapists. Summary of Key Points: The CDC's updated checklists provide clear, consistent, easy to use, and evidence-based developmental milestones to prompt discussion with families. The new checklists do not represent a lowering of standards and will likely increase, not decrease, referrals for screening, evaluation, and services. Crawling has been removed from the milestone checklists, as the current evidence suggests that crawling is highly variable and not essential for development. Conclusions and Recommendations for Clinical Practice: The updated milestone checklists will facilitate bringing vital services to children who need them. Physical therapists should support our primary care colleagues in implementing this useful program.

Infants with neuromotor disorders demonstrate delays in sitting skills (decreased capacity) and are less likely to maintain independent sitting during play than their peers with typical development (decreased performance). This study aimed to quantify developmental trajectories of sitting capacity and sitting performance in infants with typical development and infants with significant motor delay and to assess whether the relationship between capacity and performance differs between the groups. Typically developing infants (n = 35) and infants with significant motor delay (n = 31) were assessed longitudinally over a year following early sitting readiness. The Gross Motor Function Measure (GMFM) Sitting Dimension was used to assess sitting capacity, and a 5-min free play observation was used to assess sitting performance. Both capacity and performance increased at a faster rate initially, with more deceleration across time, in infants with typical development compared to infants with motor delay. At lower GMFM scores, changes in GMFM sitting were associated with larger changes in independent sitting for infants with typical development, and the association between GMFM sitting and independent sitting varied more across GMFM scores for typically developing infants. Intervention and assessment for infants with motor delay should target both sitting capacity and sitting performance.

Although early intervention for infants at risk for cerebral palsy is routinely recommended, the content of intervention is poorly described, varies widely, and has mixed supporting evidence. The purpose of this study was to compare efficacy of 2 interventions grounded in differing domains of the International Classification of Functioning, Disability and Health on developmental outcomes of infants with or at high risk of cerebral palsy. Infants who meet inclusion criteria will be randomized into either Sitting Together and Reaching To Play or Movement, Orientation, Repetition, Exercise Physical Therapy groups. Both groups will receive intervention twice weekly for 3 months and follow-up at 3, 6, 9, and 12 months from baseline. The primary objectives compare changes over time and between groups in sitting, gross motor, and cognitive development. The setting is the infant’s home unless the caregiver requests otherwise. One hundred and fifty infants between 8 and 24 months of age will be enrolled in 3 geographically, racially, and ethnically diverse sites: Los Angeles, California; Omaha, Nebraska; and Seattle, Washington. Enrolled infants will demonstrate motor delays, emerging sitting skills, and signs of neurologic impairment. Sitting Together and Reaching To Play targets activities including sitting, reaching, and motor-based problem solving to improve global development. In contrast, Movement, Orientation, Repetition, Exercise Physical Therapy focuses on strengthening and musculoskeletal alignment while encouraging repeated movement practice. Outcome measures include the Gross Motor Function Measure, Bayley Scales of Infant Development-IV, Assessment of Problem Solving in Play, and a Parent Child Interaction assessment. Enrolled children will maintain usual intervention services due to ethical concerns with intervention withdrawal. This will be the first study, to our knowledge, comparing efficacy of early physical therapy with dose-matched interventions and well-defined key principles. The outcomes will inform selection of key principle of intervention in this population.

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.