Most of the scientific community, as well as in a sector of international Law, when referring to the unborn embryo, pregnancy must be defined as the period extending from implantation to natural birth. This implies some novelty, such as the redefinition of abortion as the elimination of the embryo only within this period, and the extension of contraception to any means that impedes the union of the gametes as a consequence of a sexual intercourse, or also that which eliminates the product of conception prior to its implantation. Therefore, the pharmaceutical industry markets, under the name of contraceptives, products that act also by means of an anti-implantation mechanism. This fact has great ethical implications regarding the respect for the embryo which require a reflection on the moral valuation of the prescription, dispensation and use of these means. One may ask: which of the contraceptive means actually present in the market include an anti-implantation effect? What mechanisms contribute to their pharmacological action and in what measure do they do this? This is what we have studied in this article, based on the available scientific bibliography. We have basically fulfilled a double objective: updating and completing the studies -few, partial or distant in time- that had this same subject matter; and offering a moral valuation on the use of hormonal contraceptives that may have an anti-implantation effect, from the point of view of the respect due to the embryonic life.