Sapphira has an excellent post, mostly sums up what I want to say, but the fact that someone's beat me to the punch has never stopped me from voicing my opinion before.
I favour adoption over abortion, but am still pro-choice.
A basic assumption is that, with a very few exceptions, being alive is better than being dead. Having an abortion means that roughly one less person will be alive in the end. This, to me, is indeed a bad outcome.
However, this doesn't change my stance on abortion still being legal. I've explained my reasoning there enough times by now, I think.
This is getting a bit tangential. In essence, I don't think it's quite an "either-or" debate. Clearly in each individual situation it comes down to that but as an overall stance I think it works better to just have both. People can put up for adoption or abort as they see fit (well, there are some limits, but again, tangential at this point.) and while I'd prefer people to put kids up for adoption I'm not going to force them to at gun point, nor am I going to condemn them for not doing so.