In his 1995 encyclical Evangelium Vitae Pope John Paul II discusses the new threats against human life posed by in vitro fertilization and research involving embryos.

The various techniques of artificial reproduction, which would seem to be at the service of life and which are frequently used with this intention, actually open the door to new threats against life.

Apart from the fact that they are morally unacceptable, since they separate procreation from the fully human context of the conjugal act, these techniques have a high rate of failure: not just failure in relation to fertilization, but with regard to the subsequent development of the embryo, which is exposed to the risk of death, generally within a very short space of time.

Furthermore the number of embryos produced is often greater than that needed for implantation in the woman's womb, and these so-called “spare embryos” are then destroyed or used for research which, under the pretext of scientific or medical progress, in fact reduces human life to the level of simple “biological material to be freely disposed of” (No. 14). See McGuire Story, page. 1