"Are some forms of unnatural birth control worse than others? Yes. Those forms that act after conception has occurred to prevent the continuation of the pregnancy participate in the additional evil of abortion. "From the moment of its conception life must be guarded with greatest care, while abortion and infanticide are unspeakable crimes" (Gaudium et Spes, 51). Surgical abortion is the most obvious but not the only form. The intrauterine device (IUD) acts primarily as an early abortion agent by preventing implantation of the week-old human life. The birth control Pill makes the inner lining of the uterus very hostile to implantation. It is not known how often the Pill acts in this way, but it cannot be denied that the Pill may be acting as an early abortion agent in any given cycle in any given woman."