I was about to say "Can't those researchers just get a stem cell from the placenta instead of a fetus?" Or that "I'm quite sure that such research is not a hundred percent guarantee no matter how promising it is."
But then, for argument's sake, I'd probably not prefer that. Regardless of person's religious or irreligious background, I think it's good for us to respect human life; I mean, that fetus used to be living, just leave it alone and don't use it for profit. There could be other better options or studies to prevent miscarriages anyway. Heh, I sounded christian by saying that, but anyway, just my opinion.