THE GIST:
Mothers older than 40 were about 50 percent more likely to have a child with autism than those in their 20s. The risk for fathers older than 40 was 36 percent higher than for men in their 20s. The findings contrast with recent research that suggested the father's age played a bigger role than the mother's.A woman's chance of having a child with autism increase substantially as she ages, but the risk may be less for older dads than previously suggested, a new study analyzing more than 5 million births found.
"Although fathers' age can contribute risk, the risk is overwhelmed by maternal age," said University of California at Davis researcher Janie Shelton, the study's lead author.
Mothers older than 40 were about 50 percent more likely to have a child with autism than those in their 20s; the risk for fathers older than 40 was 36 percent higher than for men in their 20s.
Even at that, the study suggests the risk of a woman over 40 having an autistic child was still less than 4 in 1,000, one expert noted.
The new research suggests the father's age appears to make the most difference with young mothers. Among children whose mothers were younger than 25, autism was twice as common when fathers were older than 40 than when dads were in their 20s.
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