Trajectories of Posture Development in Infants With and Without Familial Risk for Autism Spectrum Disorder.

The team watched how babies learned to sit, crawl, and pull to stand. They tracked three groups: babies with an older sibling with autism, babies with an older sibling with language delay, and babies with typical siblings.

Visits happened from 6 to 14 months. Coders scored each video for the newest posture the baby could hold for three seconds.

Babies later diagnosed with autism moved through postures more slowly. They spent extra weeks in early sits and belly crawls.

Babies with only language-delay siblings were in the middle—faster than the autism group but slower than the typical group.

Sosnowski et al. (2022) widened the lens. They looked at fine and gross motor skills across three years and also saw slower paths in the autism group. The posture paper gives the close-up; the motor paper shows the long road.

Redquest et al. (2021) found that weak fine-motor grasp at 9–14 months predicted later autism likelihood. Both studies point to the same window—late first year—for red flags.

Demello et al. (1992) described older autistic kids swaying more while standing. The new work shows these balance differences start in infancy, before diagnosis.

You can spot risk without a blood test or eye tracker. Watch posture change between 6 and 14 months. If a baby sticks to early sits or belly crawls long after peers have moved on, flag for further screening and share the clip with the pediatrician. Early warning buys time for early action.