Autism : the risk increases after a first child

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Published the 25.09.2017 at 18h18

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The parents of an autistic child, may request, at the time of a second child, if it has a risk of being autistic in turn. And whether it is safe to make a risky choice. Studies had already shown that they were higher in the siblings have been affected, but a large study conducted at the medical college of Harvard has all proved, differentiating between the sexes.

They have thus demonstrated that the children most at risk are boys who have a big sister and achievement of autism spectrum disorders (ASD). They have almost one chance in five (17 %) to develop ASD in their turn. In comparison, in the general population, the risk of autism is only approximately 1 % (1,5 % in the United States).

Boys are more at risk

This figure has been extracted from a database of mutual u.s., covering more than 1.5 million families with at least two children, and about 3.1 million children. Among them, 39 000 had received a diagnosis of ASD, or about 1.2 % (2 % of males, 0.5% of girls).

Boys with a big brother with autism are also at high risk : 13 % of them are autistic. Girls are less affected. Those with a sister with ASD have a lower risk to 8 %. With a big brother, the risk is “only” 4 %.

In summary, if the first child, who has autism, is a girl, the parents have a greater risk of having a second child with ASD, especially if it is a boy.