And you forget that involuntary manslaughter can consist merely of “recklessness.” There need be no intent to hurt another for this to be found. And simply because this has not been found to date for this situation, it does not mean that the law can’t be interpreted to make this so, going forward.
http://en.wikipedia.org/wiki/Manslaughter
It wasn’t until the past century that abortion was “found” in our laws to be legal. Without a constitutional amendment that finally disallows only abortion, then the courts are left up to interpreting what they want from other cases and laws.
We either want someone who will interpret as they did originally, meaning abortion was never allowed based on original intent, or a constitutional amendment that stopped this new practice, in the absence of the Supreme Court overturning it based on some case.
As for prosecutors not wanting to go after a crime, they are required to do so, even if they don’t want to.
This is simply not true. The whole system --- cops and police chiefs, forensic investigators, prosecutors, grand juries, judges, etc. --- depends on the willingness to enforce, investigate, and prosecute, and on the practical setting of priorities. This means that some things are pursued with Inspector Jarvet-like relentlessness, and somethings are, by unspoken consensus, allowed to slide.
It's like the question of whether prostitutes are likely to be arrested on 6th Avenue, at the Star Lite Grill, at the State University Student Lounge, or in Church Square. It's all going to depend on a complaint being lodged, and that means that in some venues, either the working girls take care not to flagrantly attract offensive attention, and/or nobody gives a damn.
Bottom line: many laws are simply not priority for the system. And I repeat: nobody will investigate a miscarriage unless the woman has a traumatized cervix, an uncontrollable hemorrhage, or a septic womb.