The Impairment Argument's Coup de Grâce

According to Hendricks Impairment Argument (IA), abortion is immoral because it impairs the fetus. Here, I argue it is not sufficient to show merely that abortion impairs, Hendricks must show that it harms the fetus. If the fetus is not numerically identical to the person it will become, then it isn't harmed by an abortion. But if the fetus is numerically identical to the person it will become, it is harmed by the deprivation of a future of value. However, taking this route ultimately undermines the novelty of the impairment argument.