The risk of autistic childbearing is greater among teenage mothers and parents with age difference between them.
The largest ever-multicultural study shows the link between parental age and autism risk. The study shows the rates among children born to teenage mothers and whose parents have a relatively large age difference have higher chance of autism.
The study also confirmed that elderly parents are at higher risk of having children with autism. The analysis included more than 5.7 million children in five countries.
What to studies say about the link between parents’ age and autism?
“Although we’ve looked at autism and parenthood, and earlier, this study is not similar to any other study,” says co-author Michael Rosanoff, director of public health research at Autism Speaks. “By linking the national health registers in 5 states, we have created the world’s largest research data pool for risk factors for autism.”
“These data allowed us to see the relationship between parenthood and autism in a very high resolution, like under a microscope,” he said.
“Although parental age is a risk factor for autism, it’s important to remember that in general, most children born out of old or young parents will develop normally,” adds co-author Sven Sandin.
Although previous studies had identified a link between parenthood advancement and autism risk, many aspects remained unclear. For example, some studies found increased risk with older fathers, but not with mothers.
Specifically, the study found that Autism rates were 66% higher among children born from parents over 50 years of age than those born to fathers in their 20s. Autism rates were 28% higher when dads were in their 40s versus fathers in their 20s.
But, according to the study, autism rates were 8% higher among children born to adolescent mothers than among those born in mothers in their 20s.
Other findings about autism are:
Autism rates were 15% higher in mothers born in their 40s, compared to mothers born in their 20s.
Autism rates increase even more when both parents are older, in line with expectations that the age of each parent contributes to the risk.
Autism rates also increased by expanding the gap between the age of two parents. These rates were higher when fathers were between 35 and 44 and their partners were 10 or more years younger. On the other hand, rates rose when moms were in their 30s and their partners were 10 or younger.
“These findings suggest that multiple mechanisms contribute to the link between parenthood and risk for autism,” co-authors conclude.