Why does pain matter? You don't feel pain if you're shot in the head, either. A bacterium doesn't feel pain when it's dropped in a petri dish full of alcohol. It's still the taking of a life.
I think whether it feels anything or not is at least a little relevant. At least the fetus won't suffer if it's aborted in a safe manner.
Animal abuse is a crime primarily because animals are close enough to us where they can feel pain and we, as fellow animals, empathize with it.
From the moment it has the joined set of human chromosomes. Is a child considered not a human being simply because it's not a fully-developed adult yet? That's silly.
Again, the question isn't whether a fetus isn't human, but rather if it's a person with rights to be protected. It's a complicated issue.
The point being that if you don't want a pet anymore, you can't simply kill it without going to jail for your irresponsibility. You have to find an owner for it or take it to the pound. The funny thing is, that same law doesn't even apply to a human being.
Well it's not necessarily difficult to put up a pet for adoption. I've never done so myself, but is it that much difficult than simply taking the pet over there and signing a few papers?
Pregnancy, on the other hand, lasts a very long time (3/4's of a year) and it's not necessarily a very comfortable period for the woman. Especially if it's for a child you don't really want anyway.
I agree you that theoretically people should take responsibility for what they end up doing, but the thing is, that viewpoint, in my opinion, focuses too much on wanting to "punish" the parents, and
doesn't put the eventual well-being of the child first, which is much more important to me.
It's not impossible for an unwanted child to become a blessing in disguise, but that really depends on the situation. If you live in a well-off family with financial stability and with the means to support another child, however unwanted, it doesn't need to be bad. But not everyone is that lucky.
Adoption is another issue with its own set of problems. Rather than outright banning abortion, I think we should work on improving the adoption system first.
My main concern with the question of abortion are the special case, like rape victims and life-threatening situations. My sympathies are with the child in the case of an irresponsible mistake, but it's not my body or my business and outside of ethical considerations not much comes out of it, however much I disagree with the choice the woman is making.