When should a baby sit without support, and when is assessment needed?
Sitting develops gradually as head and trunk control improve; most babies sit without support by nine months. This is a monitoring milestone, not a diagnosis by itself. Discuss missing skills or movement concerns with a paediatric clinician and account for corrected age after prematurity.
Details
How can you help?
Provide safe floor play and supervised awake tummy time within the baby’s tolerance. Stay close during sitting practice and never leave the baby on a bed or raised surface, even when balance seems good.
Look at overall progress
The clinician considers head control, use of both sides, reaching and other developmental skills. Do not force an unsupported position or use a special seat as proof that independent sitting has developed.
Do not wait after loss of skills
Loss of an acquired ability, marked stiffness or floppiness, or clear asymmetry needs early review. Assessment may identify a role for early intervention or physiotherapy; do not wait for a distant routine appointment if concerned.
Related reading: When do children start walking, and when should delayed walking be assessed?.