Rewatching lord of the rings the two towers and the oft-memed quote from Theodin that "no parent should have to bury a child" is really a rather modern thought.
Granted LOTR is fantasy, but it is a fantasy about a semi-medieval or pre-modern world. So in the context of such a world, child and infant mortality would be rather high.
I've also had this thought when reading about Abraham Lincoln and how the death of one of his children deeply affected him.
Statistically, the chance of children surviving into adulthood has greatly increased in the last 200 years, but I'm still not quite sure how to flip that statistic to evaluate a statement like:
"being a parent before modern times typically meant having to bury a child"
Note: I am not in ANY way trying to lessen or diminish the anguish that losing a child must bring to anyone, anywhere, anytime.
If we can establish that this is the case (that before modernity, being a parent typically meant some of your children would die before you) then when did the balance flip?
Is it as simple as when surviving to adulthood increased to over 50%? Or over 71% (the square root of 50% since couples often have two children)? I think I might be doing my probablilty calc wrong here cause I'm doing it on the fly.
Source: reddit post