Mother's advanced age linked to autism

DAVIS, Calif., Feb. 9 (UPI) -- An older mother is at a significantly elevated risk of having a child with autism, regardless of the father's age, U.S. officials have found.

Lead author Janie Shelton, a doctoral student in the University of California, Davis, and colleagues obtained records for all births in California from Jan. 1, 1990 to Dec. 31, 1999.

Advanced parental age is a known risk factor for having a child with autism. However, previous research has shown contradictory results regarding whether it is the mother, the father or both who contribute the increased risk. One study reported that fathers age 40 and older were six times more likely than fathers under age 30 to have a child with autism.

"This study challenges a current theory in autism epidemiology that identifies the father's age as a key factor in increasing the risk of having a child with autism," Shelton said in a statement.

"It shows that while maternal age consistently increases the risk of autism, the father's age only contributes an increased risk when the father is older and the mother is under age 30. Among mothers age 30 and older, increases in the father's age do not appear to further increase the risk of autism."

The study, published in the journal Autism Research, found a 40-year-old woman's risk of having a child later diagnosed with autism was 50 percent greater than that of a woman between age 25-29.