What are the symptoms associated with developmental delay?

Obvious: It simply means that an infant is not meeting developmental landmarks, e.g. Sitting up, crawling, walking, speech etc.

DEVELOPMENTAL DELAY: As the child is growing up, developmental milestone is being observed and associated with other sx before DX of delay is made. Your peds will allert you if there's a problem.

Each developmental: domain has a range of ages at which typically-developing infants & toddlers reach expected milestones. Screening for these is on firstsigns.org. Not attaining a milestone by the age at which 90% of children do so is a delay. The trajectory of development over time is more important than reaching a milestone at a single point in time. Developmental surveillance is, therefore,recommended by the AAP.