Researching DS stats for one of the Palin threads the number I came across was that the odds of of a mother over 40 having a DS baby are about 1 in 30.
Today there aren’t that many women, percentagewise at least, who have children over 40. At least some who become pregnant with children with DS probably elect to abort each year- wasn’t able to find statistics.
If you back up a century, LOTS more women had children at 35 or after than do today (if not numerically then at least percentagewise). Before birth control was available or abortion was an option and large family sizes were the norm (and large families even to be wished for by some families) it was very common to see women with grandchildren older than their youngest children- in fact most of my own great-grandmothers would have been capable of nursing their oldest grandchild. On almost every page of the census, at least in rural areas, you’ll see entries like
The gaps in the older children generally being adult kids who have married and or left home.
Women weren’t just more likely to have kids when they were 35 than women today are over but they were likely to have more kids after the age of 35 than women today are. Mothers as old as 48 or so when the youngest was born aren’t that terribly uncommon, and the youngest child rarely had a really sizeable gap (like 15 or 20 years) between them and the next sibling up.
The Census records recorded (pardon me for using the terms, but it’s what was used) “blind/idiot/insane” in various records, but they didn’t usually indicate or specify a particular diagnosis. “Idiot” could mean retarded or even such things as epilepsy or cerebral palsy in which the child/adult’s mind was actually perfectly good but their body had serious issues. (I have read the term “Mongolian idiot” in literature of the early 20th century describing a 22 year old girl who was pregnant [this was while researching eugenics] which I assume was the pre- PC term for Down’s Syndrome.)
Anyway, just curious: I’ve done some googling but not any really in-depth research. Does anybody know if there were more DS children (or children who had other congenital defects more common among children of older parents) in previous generations than now? You don’t tend to hear of them, and if the answer is yes it’d be interesting to research how they addressed the issue and if no then it’d be interesting to learn why not.