I consider cases of multifetal pregnancy in which one fetus with a fatal birth defect poses a risk to the survival of another healthy fetus to show that the substance view anti-abortion position leads to a contradiction. In cases of complicated multifetal pregnancy, if intervention by selective abortion to terminate the defective fetus is not performed, both fetuses will die due to the conditions created by the defective fetus’s fatal birth defect. Because abortion is wrong on the anti-abortion position, and (...) a moderate anti-abortion position cannot make an exception for selective abortion in cases of complicated multifetal pregnancy if it operates on the substance view, choosing selective abortion must be wrong, so one must let both fetuses die. However, the substance view anti-abortion position must take letting both fetuses die to be wrong, otherwise it will undermine itself as an anti-abortion position. Further, the substance view provides grounds for why letting fetuses die would be wrong anyway. Thus, the substance view anti-abortion position must take both having an abortion and not having an abortion to be wrong, which is a contradiction. Therefore, cases of complicated multifetal pregnancy show that the substance view anti-abortion position is false. (shrink)