RISK FACTORS

The exact cause of autism spectrum disorder is not known.

It is believed that both genetic and environmental factors are involved. These influences appear to increase or decrease the risk that for a child to be autistic.

It’s important to keep in mind that increased risk is not the same as cause. For example, some gene changes associated with ASD can also be found in people who don’t have the disorder. Similarly, not everyone exposed to an environmental risk factor for autism will develop the disorder. In fact, most will not.

Genetic risk factors

If one or several family members have autism, especially in the case of a sibling or twin

Certain gene changes carried in one or both parent(s), the sperm and/or egg that combine to create the embryo, or in the early embryo itself

Environmental risk factors

Importantly, the increase or decrease in risk appears to be small for any one of these risk factors.

Increased risk

Advanced parent age (either parent)

Pregnancy and birth complications e.g. extreme prematurity, low birth weight, multiple pregnancies

Pregnancies spaced less than one year apart

Decreased risk

Prenatal vitamins containing folic acid, before and at conception and through pregnancy