"Into this world"

I have an honest question for those who assert that abortion should be allowed at any time before birth (although this question also applies to those who only support abortion up to a certain point) because, if a person doesn't want to, they shouldn't have to "bring a child into this world."  My question is this: isn't the baby already in the world?  Just because you can't see an unborn baby (with the naked eye; you CAN see her with ultrasounds) doesn't mean that she isn't "in the world" already.  They are behind some layers of skin and muscle, not in another dimension.