Delayed milestone, also called developmental delays, is used to describe the condition where a child does not reach one of these stages at the expected age. However, in most cases, a wide variety of ages can be considered normal, and not a cause for medical concern. Milestones are often measured using percentiles, and for many milestones a value between the 5th and 95th percentile does not require intervention, though values towards the edges of that range can be associated with other medical conditions. It is not possible to treat. It has been suggested that measurement of posture sway may be an early indicator.
- ^ Deffeyes; Harbourne, R.; Kyvelidou, A.; Stuberg, W.; Stergiou, N. (2009). "Nonlinear analysis of sitting postural sway indicates developmental delay in infants". Clinical biomechanics (Bristol, Avon) 24 (7): 564–570. doi:10.1016/j.clinbiomech.2009.05.004. PMID 19493596.