Why can't the father have a say in whether a woman keeps his baby?

This has always been so unfair to me. Yeah, I know the woman has to go through all the bodily changes and actually have the baby...blah blah blah. But it still takes TWO to actually create the child, so why does only one (the mother) have the final say in what happens to the child if it takes two to create it? I mean women always use that same it takes two crap when it comes to dead beat dads, so why doesn't the same thing apply here?