Since no method of contraception is 100% effective, there may be certain circumstances where pregnancy may be undesirable for a multitude of reasons - possible genetic defects, threat to health of the mother to name but two.
It's an emotive issue and I guess I could say I was pro-choice, but being neither female nor a parent as a result cannot speak from any perspective of experience. Because it's such a thorny issue I don't feel wearing a T shirt with "I had an abortion" emblazoned across it is a particularly sensitive thing to do.
But then I don't necessarily like the idea of T shirts with "Cocaine" or "Crack Whore" printed on them either.