A study out of UC Davis says autism rates in California have gone up, in part, because the average age of child bearing has gone up. But the effect has not been dramatic.
Nobody knows why autism has become so widespread. But researchers at UC Davis say one reason is the increasing age of women who bear children. Their study examined records of 5.6 million children, born in California between 1990 and 1999. It showed the risk of having an autistic child increased 18 percent for every five-year increase in a woman's age. Still, lead researcher Janie Shelton said that's a small part of the autism increase.
"Even though mothers are having children later," she said, "and they are at higher risk of having an autistic child, it doesn't account for the steep increase we've seen in California. It accounts for less than five percent, and we estimate the increase to be somewhere around 600 percent."
But Shelton said if we can determine why maternal age affects autism, it would provide an important piece in the autism puzzle.
