In his classic paper, 'Why abortion is immoral', Don Marquis argues that what makes killing an adult seriously immoral is that it deprives the victim of the valuable future he/she would have otherwise had. Moreover, Marquis contends, because abortion deprives a fetus of the very same thing, aborting a fetus is just as seriously wrong as killing an adult. Marquis' argument has received a great deal of critical attention in the two decades since its publication. Nonetheless, there is a potential challenge to it that seems to have gone unnoticed. A significant percentage of fetuses are lost to spontaneous abortion. Once we bring this fact to our attention, it becomes less clear whether Marquis can use his account of the wrongness of killing to show that abortion is the moral equivalent of murder. In this paper, I explore the relevance of the rate of spontaneous abortion to Marquis' classic anti-abortion argument. I introduce a case I call Unexpected Death in which someone is about to commit murder, but, just as the would-be murderer is about to strike, his would-be victim dies unexpectedly. I then ask: what does Marquis' account of killing imply about the moral status of what the would-be murderer was about to do? I consider four responses Marquis could give to this question, and I examine what implications these responses have for Marquis' strategy of using his account of the wrongness of killing an adult to show that abortion is in the same moral category.