One additional factor is that it is theorized that a heck of lot of those miscarriages are in fact the body spotting something fundamentally wrong with the pregnancy and going "Abort, Retry". One would certainly want to examine if this is the case before proceeding on a project to stop it from doing so. Not that this seems like a very easy project. I mean.. what is the research team supposed to do? Collect feminine hygiene pads from women trying for children and go through them for cell samples to analyze? That really sounds like a very.. obnoxious. project to set up. Persuading at least several hundred would-be mothers to consign their menses to a cold chain for starters. Logistics hassle from heck.