The lefts motivation is to avoid responsibility. Making it a "womans body / womans choice" issue is plausible enough they can lie to themselves about their own true motive. This is why to them its never enough that abortion is legal it has to also be socially acceptable which is why they continue to push the issue even though they already won. They are trying to accept themselves by forcing you to accept their choices when they know deep down they are avoiding responsibility and doing something terrible. To answer your question, they are making a deal with the devil. They give up their unborn offspring and in return they get absolved of their responsibilities.