In the Sutherlands Springs massacre, one of the victims was 8 months’ pregnant. How long would the baby have survived in utero after the mother was shot? Would it have been long enough for an emergency cesarean? (q.v. Malcolm in MacBeth)
There have been instances of dead pregnant women where the baby was saved. You only have minutes to act, though - once the mother’s heart stops the baby is not getting oxygen anymore.
“Mother is dead” was the original form of c-section, as slicing open a living woman to the extent necessary in primitive conditions without modern medical care was pretty likely to result in her death if she wasn’t already in that state. Once in a very great while a woman might survive that, but it was very much the exception and not the rule.
That’s where Saint Raymond the Unborn gets his sobriquet. And yeah, basically it’s a “fuck she’s dead where’s my biggest knife” kind of situation.