Like iago said, this is just another one of this speculative arguements that'll never end.
Personally, I'm for abortion.
Situation: Mom is going to have a baby.
Probable causes for getting abortion:
1. Can't afford it. A baby is very time and money consuming, and I'm sure many people can get into a situation where they will be pregnant and be unable to provide financial support. If this is the case, then both the mother and the kid will suffer from poverty, which will fuck up the kid even more than a mother who couldn't afford him/her in the fist place.
2. Doesn't want it. The mom might completely hate the thought of having a child of her own, and then what will become of the child? The mother will be forced to nurture and raise a child that she didn't want in the first place. Or, the child might go into an orphanage, and we all know that that'll bring loads of fun in that person's life. Sure, I'd choose an orphanage over death but the babies don't have the conscience to make that choice.
I just used the mother in this example. I could mix in the father and add a few more reasons but those are too extensive.