Although not quite first hand experience, my sisters friend was told she had a 0% chance of survival. She went on with the pregnancy anyways. She survived it. Medicine is an art more than a science at times. There are too many different factors for everything to be known. (for the record, I do agree that in this type of situation, abortion would be what should be done, however, Im just playing devils advocate)
Sadly, there is a political set of terminology that is used that is never restated in stories like this. Their is 0% of survival and near 0% chance of survival. 0% of survival, the heartbeat stopped, severe ectopic pregnancy, certain genetic diseases. In these cases a doctor not looking to get sued will say, I'm sorry to inform you.... these are your options, (DNC only or a choice of DNC and natural miscarriage depending on what is going on).
Now there are other near 0% chance of survival, such as if the cysts on the ovaries don't stop growing and they are are filling rapidly. In this case, the mother most likely will die from internal bleeding if the cysts are compound cysts and rupture poorly, or the womb will be turn or ripped, etc, If the pregnancy get's even near the third trimester, the baby if still alive if not crushed to death or cut off from oxygen, will likely be severely deformed and brought into the world to live a miserable life of pain and suffering. So a doctor not looking to get sued will say, you have a choice to keep going with this pregnancy, it's very very risky and either you and/or the baby have a next to nothing chance of survival; however, it is still possible and so you have a choice here.
It's likely a case like this where their was a severe risk that is a personal choice to make, she chose to go forward, in your story we have no idea the state of the child, lets hope healthy and well, we have no current knowledge of the status of the mother, lets hope healthy and well, and so a choice was made, and in the statistic risk side, she defied the odds. It's that, that falls in my number 2.) catagory. It's the grey area, which when one thinks, educates, and makes the best decision, results in catagory 1.) or catagory 3.), She found this fall into category 3.) and then said do I want to keep it, absolutely, and proceeded.