Why would maternal age be associated w/ an increase in errors that lead to Down Syndrome?
Maternal age influences the chances of conceiving a baby with Down syndrome. At maternal age 20 to 24, the probability is one in 1562; at age 35 to 39 the probability is one in 214, and above age 45 the probability is one in 19.[72] Although the probability increases with maternal age, 80% of children with Down syndrome are born to women under the age of 35,[73] reflecting the overall fertility of that age group. Recent data also suggest that paternal age, especially beyond 42,[74] also increases the risk of Down syndrome manifesting.[75] Current research (as of 2008) has shown that Down syndrome is due to a random event during the formation of sex cells or pregnancy. There has been no evidence that it is due to parental behavior (other than age) or environmental factors.
