There are many factors to take this decision, but mainly in how long in the term is the fetus and the resources situation of the family (work, economic, external support, their health, etc).

In an ideal world though, induced abortion should not exist since it is the society who should completely support, and adaptively to the children' special needs, but when society fails at that and, so far, #all societies are, it is the family and doctor the only ones who should only make the decision on a fetus. The only argument today should be when a fetus becomes a human.

We should treasure far more families that dedicate more than the usual percentage of resources to take care of their weakest of their members (children or parents) than basically anyone else in society like we do with youtubers, sport players, oligarchs, politicians, etc.