The Mishna (Bekhorot 8:2) refers to two children born to the same mother, the first by C-section and the second by regular delivery. The Rambam famously comments that it seems exceedingly strange to him that a woman would even survive a C-section, let alone go on to deliver another child healthily, and the US National Library of Medicine suggests that the earliest record of a mother surviving the operation at all might have been as late as 1500.
I'm comfortable with this mishna (like many of the mishnayot in this tractate) being hypothetical; my question is, under which circumstances would a living woman have been subjected to this procedure in the first place? If it carried with it such a high possibility of her not surviving, and since her life takes precedence over the life of her unborn baby, would there have even been a situation in which the halakha allowed it to be performed on a living person?