My mom had me at the age of 40. As a special ed. teacher, I have learned that the risk of having a child with down syndrome is higher for women at mid age and it's sometimes harder to conceive. Otherwise, if your doc says you're healthy enough go for it, they will probably just test your fluid while you're pregnant for the down syndrome.
The problem would not necessarily be maternal complications, but you are bucking longer odds for the child in terms of Downs and other issues. My neighbor has seven kids, and though she was only 41 when she had the last one, he does have Downs. So there is no particular protection in having had a long string of kids without it, once you get to a certain age. She is not worried that her son has Downs, it's just a different set of challenges, and if you would feel that way too, go for it.