If the foetus in the womb is presenting a lethal threat to the life of the mother, does she not have the right to defend herself?

I think here, for example, of the 9 year old Brazilian girl who was repeatedly raped by her stepfather, and became pregnant with twins. Weighing only 80 pounds, the medical professionals found that her life was at risk ... that it was highly improbable that she would survive were she to try and bring them to term. Is this not a case for prudential judgement, with justification?