That people actually think in this terms and believe this provides a justification for abortion(if this is true, anyways), it's just an example of how disgusting utilitarism and, in Schopenhauer's words its constant companion, ignorance, truly is.
There is no need for a 'justification' of abortion, as it is a private act taking place within someone's body, and clearly none of your business. The reduction of crime argument is just a side benefit, as well as a useful way to expose the role inequality, class, and lack of social mobility have in our capitalist society.