I found the following on the site listed below. I believe this piece of information came from "Confessions of a Medical Heretic" by Robert S. Mendelsohn, MD.
Mrs. D.B., AZ
Then there's the well-meaning friend who reminds you of Downs Syndrome at your age (I'm 45). Mary, God doesn't make mistakes and I believe they will find some day that age isn't a factor. [They may have found so already. Dr. Mendelsohn tells of research that shows it's the amount of radiation you have received, not age, that is the decisive correlating factor. It just happens that older women as a group have had more opportunity to be X-rayed, etc. - Ed.] Otherwise, why do so many younger women have Downs babies? He wouldn't have made it possible for us to still bear children in our forties and then have us full of defective eggs. It doesn't make sense.