I found this on
exceptionalmarriages.com:
The Church teaches that “direct abortion, that is, abortion willed as an end or as a means, always constitutes a grave moral disorder,” and is “intrinsically illicit.” One may not take an unborn baby’s life even as a means to the end of saving the mother’s life - even if the baby will die “anyway” (we will all die “anyway,” later if not sooner).
This does not, however, mean that basic virtue, or even sanctity, require a woman to forgo a life-saving procedure that would cause as a “side effect” the death of her unborn baby. She may avail herself of such a procedure - even if refusing it (and thus accepting her death) would save the baby (again, that is not the issue). In such cases, “double-effect reasoning” comes into play. Thus - for instance - suppose a woman is in the early stages of pregnancy, and is also diagnosed with uterine cancer. She is told that if she waits to have a hysterectomy until the baby is viable, the cancer will have become incurable. She may certainly have the operation. The choice to remove a cancerous organ is good in itself; the intention to save the woman’s life is good; the operation does not achieve this good effect by means of taking the baby’s life (after all, the operation would have its good effect even were the mother not pregnant) - the baby’s death is, rather, a “side effect”; the saving of the mother’s life is “proportionate” to the baby’s death.
Now, of course, the opposite choice could also be morally licit! (In fact, this is also explained - the choice is distinguished from suicide - by double-effect reasoning). If a mother’s death would result in the unborn baby’s death also, then I don’t see a reason to forgo measures that would save her life, even those that would have as a “side effect” the death of the baby. But if the baby could be saved, then it could certainly be in keeping with “heroic virtue,” and sanctity, for a mother to make the choice of which St. Gianna spoke.
But such a choice is not necessary for virtue and sanctity (and in some cases, might not even be prudent - depending on what other obligations to others the woman might have).
Nicole