Developmental milestones in toddlers with atypical development.

Horovitz et al. (2011) watched five groups of toddlers with different diagnoses.

They wrote down when each child first crawled, walked, and spoke a word.

Kids had Down syndrome, cerebral palsy, global delay, seizure disorders, or were born early.

Children with seizures or prematurity crawled and walked sooner than the other three groups.

All groups said their first word at about the same age.

The study only describes the pattern; it does not test why it happens.

Wilson et al. (2024) extends this work. They found that autistic toddlers who walk slowly also score lower in talking, moving, and daily skills even when they start walking on time.

Sievers et al. (2020) narrows the lens. In kids with ASD tied to certain gene changes, the exact age of first walking and talking predicts later IQ and daily living scores.

Li et al. (2023) adds another layer. In babies with autism in the family, early gross-motor and receptive-language delays together forecast higher autism traits later.

These papers do not clash with Horovitz et al. (2011); they simply move from description to prediction.

You can use milestone charts, but do not stop at the calendar age. Note the child’s pace and quality of movement and how well they understand words. If a toddler walks on time but slowly, or shows both motor and receptive-language lags, plan extra assessment and target both areas in intervention.