There are various known causes of mental retardation, including genetic disorders, maternal infections, psychosocial conditions, drug exposure, and environmental chemical exposure. The established risk factors for MR include: [3]
- Various genetic disorders (e.g. Down’s Syndrome, phenylketonuria)
- Certain maternal infections during pregnancy (e.g. rubella)
- Mother who abuses substances such as alcohol during pregnancy
- Certain psychosocial conditions (e.g. problems with caregiving, low socioeconomic status, low parental education)
- Maternal exposure to various drugs (e.g. thalidomide, valproic acid)
- Maternal exposure to environmental chemicals (discussed in detail later)
The expanding scientific knowledge base has led to a rejection of the simplistic debate over "organic" versus "environmental" causes of retardation. There is a growing recognition of the interactive contributions of nature and nurture to the development of all children. [4]