"Development" refers to the changes in a child as he or she progresses from an immature infant to a capable, mature adult. Illness or injury to a child who is still developing can often influence how the child continues to develop, even after he or she has recovered from the actual illness or injury. Because changes in development are gradual and occur over time, it is not always possible to determine whether the developmental process will be adversely affected by early illness or injury until months or even years have elapsed.
"Developmental Delay" is a term used to indicate that development is proceeding slower than expected for a normally developing child. It does not imply anything about whether or not the child can be expected to eventually "catch-up" or attain a normal rate of development. Developmental delay can occur temporarily, perhaps due to illness or environmental factors (e.g., long-term supplemental oxygen, hospitalization, etc.) or it can be an indication of a long-term developmental disability which will never fully resolve (e.g., cerebral palsy, mental retardation, etc.). Most prematurely born infants, and many full-term infants who have neonatal problems, will experience temporary delays in development during infancy related to long hospitalizations and/or restricted physical activity, etc. Some of these infants will also have sustained some damage to their developing nervous system that will not become apparent until sometime later in their development. Whether the delay is a temporary condition or one that will continue into adulthood, "developmental delay" will typically be used until the child meets the criteria for a more appropriate diagnosis (e.g., cerebral palsy, mental retardation) or until he or she catches up with others of the same age.