In Health Watch:The chance of giving birth to a child with autism..significantly increases with a mother's age.This according to a new study.The University of California Davis Health System study looked at more than five million births in California during the 1990's.It found the incremental risk of having a child with autism increased by eighteen-percent for every five-year increase in the mother's age.Dr. Hertz-Picciotto says, 'we don't know how much of the increased risk is biological and how much of it is because the women who delayed childbearing tend to be more educated and have more access to healthcare, and therefore their children are getting diagnosed more effectively.'The risks were associated with older mothers regardless of the father's age with one exception: If the mother was under 30... an older father - did increase the autism risk.Doctors stress that parents should never blame themselves.