Advanced maternal age is linked to a significantly elevated risk of having a child with autism, regardless of the father's age

Advanced paternal age is associated with elevated autism risk only when the father is older and the mother is under 30. Scientists found that the incremental risk of having a child with autism increased by 18% - nearly one fifth - for every five-year increase in the mother's age. A 40-year-old woman's risk of having a child later diagnosed with autism was 50% greater than that of a woman between 25 and 29 years old.