Possible Causes

There are a multitude of etiologies for developmental disabilities. The cause
can be prenatal, perinatal, or postnatal. Risk factors for developmental disabilities
can be biological, environmental, or a combination of both. Genetics
plays a role in conditions such as Tay-Sachs disease and other inborn errors
of metabolism, Klinefelter’s syndrome, Fragile X syndrome, and Down
syndrome, that typically lead to developmental disability. Genetic causes
may be chromosomal abnormalities, single gene defects, or multifactorial
disorders. For example, autism appears to have a genetic component that
interacts with developmental factors.
A number of conditions in the prenatal environment may increase the
likelihood that a child will be born with the potential for a developmental
disability. Fetal alcohol syndrome, for example, is completely preventable if
pregnant women do not drink alcohol.Women who have sufficient amounts
of folic acid in their diets reduce the risk of having a child with a neural tube
defect that can result in a developmental disability.
Smoking during pregnancy, use of certain drugs such as cocaine or heroin,
poor maternal nutrition, and extremes of maternal age greatly increase
the chances of fetal brain damage or premature delivery and low birth
weight. Babies with low birth weights are three times more likely than normalweight
babies to have developmental disabilities. Approximately 61 percent
of premature infants have a developmental disability of some kind.
Children may later be at risk through environmental causes such as lead
poisoning, inadequate nutrition, infections, nonstimulating environments,
abuse, neglect, and traumatic brain injury.