On this interpretation of Exod 21:22-25, it is of particular importance for the biblical view of the nature of the fetus that the life-for-life formula is applied to the destruction of the fetus, with no qualification as to how young the fetus might be. The fetus, at any stage of development, is in the eyes of this law a living being, for life (nepes) is attributed to it. To be sure, the life-for-life formula is also used in the case of the death of animals (Lev 24:18), so that this formula by itself does not establish that the referent is a human being. But if it is the fetus of a human mother that is identified by the life-for-life formula as a living being, there can be no question that this living being is a living human being. Significantly, the part of the talion formula specifying injuries to eye and tooth and the like is not applied to animals. Only in the case of human beings do these features take on the value that merits legal redress. And surely the living fetus in view when the talion formula mentions the loss of life (v.23c) must be identified with the human child referred to in the talion formula as suffering the loss of eye or tooth (vv. 24, 25). Consistently in the relevant data of Scripture a continuum of identity is evident between the fetus and the person subsequently born. And Exod 21:22-25 makes clear that this prenatal human being is to be regarded as a separate and distinct human life.
As we observed at the outset, induced abortion was so abhorrent to the Israelite mind that it was not necessary to have a specific prohibition dealing with it in the Mosaic law. The Middle Assyrian laws attest to an abhorrence that was felt for this crime even in the midst of the heathendom around Israel, lacking though it did the illumination of special revelation. For in those laws a woman guilty of abortion was condemned to be impaled upon stakes. Even if she managed to lose her own life in producing the abortion, she was still to be impaled and hung up in shame as an expression of the community’s repudiation of such an abomination. It is hard to imagine a more damning commentary on what is taking place in enlightened America today than that provided by this legal witness out of the conscience of benighted ancient paganism.
From Lex Talionis and the Human Fetus by Meredith G. Kline