Could you explain what is delayed motor development?

Expectations: We expect newborns to meet certain milestones in development to consider their progress normal. Infants are expected to roll over at 4-5 mo, get to sitting by 9 mo, pul to stand by 9-12 mo and walk independently by 12-15 mo. All of these features require the interplay of muscle control, balance and emerging talents.A kid is not meeting these motor milestones is delayed.Causes need to be explored.

Each developmental: stream - cognition, communication, social, fine motor & gross motor- has a range of ages in months at which typically-developing infants achieve specific skills. An infant who does not attain those skills by the age at which 90% of infants demonstrate them has a delay in that stream. Fine motor = use of muscles of the upper trunk, arms & hands; Gross Motor = use of muscles of pelvis,legs, feet