A new study, lead by Neil Risch of the University of California, San Francisco, analyzed the public health records of some 20,000 families featuring at least one autistic child in California.
"While it has been postulated that parents who have a child with [autism] may be reluctant to have more children, this is first time that anyone has analyzed the question with hard numbers," said Risch.
In analyzing the 20,000 California families touched by autism, Risch and his team of researchers were able to show that parents were significantly less likely to having a second child after a their first is diagnosed with the social disorder. Further childbearing takes a similar hit in the wake of a second or third child with autism.
While the conclusion may seem obvious, the confirmed results are significant for calculating the chance that a couple's second child will be autistic after the first is diagnosed. Before scientists factored in the reality that so many parents were choosing to forego further childbearing in the wake of a diagnosis, the estimated risk was 8.7 percent. But factoring in these new findings move that number up to 10.1 percent.
"These findings have important implications for genetic counseling of affected families," said Risch.
The study was published this week in the journal JAMA Psychiatry.