I suspect you have never faced this decision before. Lucky you.

In fact, both cases are the woman deciding what she is willing to do, what she is willing to live with, what risks she is willing to take based on the evidence before her and the advice of geneticists. It is, after all, her body in both cases.

The fetus cannot decide whether it wants to go through with developing and being born or not. That isn't an option here, given the immaturity of the fetus and those pesky limitations of space-time. The woman must decide. You would take that choice from her?