Maternal age: The age of the mother at the time of delivery. Advanced maternal age is usually defined as age 35 or more at delivery.
Advanced maternal age predisposes to Down syndrome (trisomy 21). The risk of having a Down syndrome baby rises with maternal age. It essentially doubles from 1 in 725 at maternal age 32 to 1 in 365 at maternal age 35. And the risk continues to climb with the years and is 1 in 32 at maternal age 45.