Motor development milestones: what's expected and when to worry

Quick answer. Babies with Down syndrome reach the same motor milestones as any other baby — sitting, crawling, standing, walking — in the same order, but later and with more variation from child to child. What matters isn’t the exact age, it’s that the sequence keeps moving forward.

Why it matters. Hypotonia (lower muscle tone) and some differences in body structure make motor development slower — on average, 2 to 3 times slower than in children without Down syndrome. Knowing this ahead of time keeps an expected delay from feeling like an alarm every week.

What the source says. Studies on motor development in Down syndrome document ranges like these: sitting without support, on average at 9 months (range 6–16 months); standing without support, on average at 18 months (range 12–38 months); walking without support, on average at 24 months (range 16–42 months). That range is wide on purpose — everything inside it counts as typical development for a child with Down syndrome. What specialists recommend watching isn’t the age itself, but whether the sequence of milestones keeps moving forward, even slowly.

What can you do now? Contact your local early intervention program as soon as possible — you don’t need to wait to see a “big” delay to start. Early physical therapy helps build foundational motor skills and can help prevent joint discomfort later on.

To go deeper. NDSS — Early Intervention: how early intervention works and how to access it in your area.