Although the exact cause or causes of ASD are not know, most experts tend to believe that there may be many different factors that can make a child more likely to have an ASD (including environmental, biologic and genetic factors). One or more of the following may be considered risk factors for developing ASD:
- Most scientists agree that genes are one of the risk factors that can make a person more likely to develop ASD.
- Children who have a sibling with ASD are at a higher risk of also having ASD.
- ASD tends to occur more often in people who have certain genetic or chromosomal conditions, such as fragile X syndrome (Centers for Disease Control and Prevention (CDC): Facts about Fragile X Syndrome) or tuberous sclerosis.
- When taken during pregnancy, the prescription drugs valproic acid and thalidomide have been linked to a higher risk of ASD.
- There is some evidence that the critical period for developing ASD occurs before, during, and immediately after birth.
- Children born to older parents are at greater risk for having ASD.
At present, the CDC is currently working on one of the largest US studies to date to seek possible risk factors for ASD including genetic, environmental, pregnancy, and behavioral factors. The study is termed the Study to Explore Early Development (SEED). Information is available from the CDC at
SEED.
