A new study linking parental age to autism has found women who gave birth when they were over 40 were two times more likely to have autistic children than women who conceived and gave birth before 25. Fathers over 40 who had significantly younger partners had a pronounced increase in the number of autistic offspring, as well.
The study, published online in the journal Autism Research, looked at 5 million births in California during the 1990s. More than 12,000 of the babies were diagnosed with autism — a large en0ugh sample for further statistical analysis. From these numbers, they concluded the following:
Independent of the father’s age, women over 40 were 77 percent more likely to have a child with autism than women under 25.
The older moms were 51 percent more likely than those 25 to 29 years old.
For men over 40, there was a 59 percent increase in risk of autism if the mother was under 30. But no increased risk if the mother was over 30.
Researchers are quick to say there is not a direct correlation between parental age and autistic children. Instead, the findings offer direction for more research.
In the 1990s, births to California women over the age of 40 grew 300 percent. But the number of children diagnosed with autism grew sevenfold over that same decade.
From the New York Times:
“The rise in autism is occurring among children of parents of all ages,” said Janie F. Shelton, a graduate student in epidemiology at the University of California, Davis, who was the paper’s lead author. “We can’t say that the shifting trend of maternal age is responsible for the increased rates of autism.”
Age is a factor, they’re saying, but not the only one. There has been a rise in autism rates for every age group. And it’s not clear what about age would be contributing to the increased rates.
Meaning what? More study is necessary.