Christopher O. Tollefsen argues that accepting the “liberal” definition on pregnancy can actually help clarify the morality of contraception, abortion, and embryo adoption:
Liberals and conservatives sometimes spar over the definition of pregnancy. Some liberals define the term as meaning the period from implantation of an embryo in a mothers womb forward. Conservatives often define it as beginning at the point of conception. Quite a lot can seem to depend on the definition, since it can seem natural to think that a contraceptive, for example, works by preventing pregnancy, and an abortion by disrupting it. Thus, if pregnancy is not initiated until implantation, and an abortion disrupts pregnancy, then drugs that prevent implantation would be considered contraceptive, and not abortifacient. Conservatives rightly resist this claim, and do so by contesting the meaning of pregnancy.
But a better strategy might be to accept the liberal definition of pregnancy, but reject the conclusions that purportedly follow from it. On three issuescontraception, abortion, and embryo-adoptionIll argue that the liberal definition of pregnancy can actually help clarify what sound morality demands.