Developmental problems are referred to under the umbrella term “developmental delays,” which describe any ongoing delay in a child’s meeting age-specific developmental milestones (as opposed to physical growth). To be a genuine medical symptom (as opposed to a child’s temporary lag in one area, which is normal), a developmental problem must affect a chain of developmental milestones and must be ongoing. Most developmental problems are recognized before the child’s second birthday.

Development problems fall into several categories affecting ongoing functional developmental milestones. These milestone categories include language skills, cognitive development (thinking and learning), social and emotional development, and gross motor and fine motor skills. Most developmental problems cross over, combining several types of developmental milestones or problems within one disorder.

Causes of developmental delay are widespread, but include inherited disorders, mental retardation, neurological damage, autistic disorders, degenerative diseases, social or environmental deprivations, deafness, and many more causes. Infants with unrecognized (treatable) medical conditions, such as congenital hypothyroidism, can have symptoms of developmental delay. Some developmental problems can be corrected or improved by addressing causes such as poor vision, deafness, and environmental factors.