NC
It is a serious thing, but more importantly it is real. It isn’t abstract. I’m familiar with several such cases and am aware of much more.
Kids are taught things simply black and white. If it is pikuach nefesh you eat on yom Kippur otherwise you fast.
The reality is much grayer. A doctor cant predict if X fasts on Yom Kippur he will die. It just doesn’t work that way.
Rabbonim’s job (with medical guidance if needed) is to figure out where people fall can they fast? must they fast ? if they should break their fast is it with shiurim or just eat ? If they can eat should they at leat attempt to fast and see how it goes? a few hours or attempt the whole day ?
not everybody falls into a must fast vs must eat category
furthermore, at times Rabbonim are more “lenient ” Particularly when it comes to pregnant woman as I explained above.
As for the topic at hand. Take Anencephaly there, is generally no MEDICAL (as opposed to psychological) reason to abort. while of course tragic and the fetus won’t survive there is no medical reason to terminate. Of course psychological stressors is obviously much greyer. If she were to develop a nervous breakdown and be at risk for suicide, r”l again that is a reltivly easy psak. but as you may realize that is not really how psychiatry generally works. what if her mental/emotional/physical health is at risk but not quite her life?
R’ Moshe did not allow abortions in such cases. the Tzitz Eliezer was very meikel. R”shlomo Zalman allowed it as well (though stricter than Tzitz Eleizer) Modern Poskim (especially chasidish ones) tend to allow it though not late into pregnancy .
This is but one specific example
R’ Ben Zion Uziel allowed abortion even late into pregnancy to prevent deafness (not death ) of a mother.
In all these cases it obviously wasn’t REQUIRED.