The Pull-to-Sit Task: Examining Infant Postural Development in Autism Spectrum Disorder.

Objective: To evaluate the predictive relationship between early trajectories of postural and head control during a pull-to-sit task and later autism diagnostic and developmental outcomes.

Study Design: Using a prospective longitudinal design, postural skills of 100 infants at elevated and low familial likelihood of autism spectrum disorder (ASD) were evaluated using a pull-to-sit task monthly from age 1 month to 6 months. At age 24 months, infants were seen for a developmental and diagnostic evaluation completed by examiners masked to participant group. Latent growth curve models were used to compare early trajectories of pull-to-sit performance in infants later diagnosed with ASD and typically developing infants and to predict developmental outcomes.

Results: Pull-to-sit trajectories did not differ in infants with an elevated likelihood of ASD or infants with ASD compared with low-likelihood and typically developing infants, but infants with ASD were more likely to exhibit a head lag by age 4 months. In addition, pull-to-sit trajectories were predictive of social and speech skills 2 years later.

Conclusions: These findings highlight the link between very early pull-to-sit skills and later social and language outcomes. Atypical postural development and persistent presence of head lag may be important early indicators of social and language vulnerabilities, including ASD.