Nor did the Catholic Church treat abortion as murder in the past. If it had, late-term abortions and miscarriages would have called for treatment of the well-formed fetus as a person, which would require baptism and a Christian burial. That was never the practice. And no wonder. The subject of abortion is not scriptural. For those who make it so central to religion, this seems an odd omission. Abortion is not treated in the Ten Commandments -- or anywhere in Jewish Scripture. It is not treated in the Sermon on the Mount -- or anywhere in the New Testament. It is not treated in the early creeds. It is not treated in the early ecumenical councils.
Mirror of Justice helpfully provides an opinion from Joseph Dellapenna, who has written a magisterial legal history called Dispelling the Myths of Abortion History( see the First Things review).
Why this neglect of abortion in the ancient sources? The answer, which is mostly forgotten today, is that abortion until fairly well along into the nineteenth century was tantamount to suicide. Women rarely, if ever, underwent a voluntary abortion. We in fact have a significant number of legal cases from as far back as 1200 in England and even earlier in Roman law, in all of which the abortion was forced upon an unwilling woman. This simple fact is reason enough why the Bible and most other legal and religious sources from that time treated as an abstract, a hypothetical idea. I have elaborately documented the evidence for the techniques of abortion in chapter 1 of my book. The real social problem, which was addressed in detail and repeatedly in legal and religious sources, was infanticide—a social problem that only receded in importance with the development of abortion techniques in the late nineteenth and early twentieth century that were safe enough for women wanting to be rid of an unwanted child to be able to choose abortion in preference to infanticide.
Furthermore, Wills' assertion that there was no practice of baptizing miscarriages looks doubtful. The Catholic Encyclopedia's article on Baptism actually has a section titled "Baptism of Unborn Infants." It states:
In case of the death of the mother, the fetus is to be immediately extracted and baptized, should there be any life in it. Infants have been taken alive from the womb well after the mother's death. After the Cæsarean incision has been performed, the fetus may be conditionally baptized before extraction if possible; if the sacrament is administered after its removal from the womb the baptism is to be absolute, provided it is certain that life remains. If after extraction it is doubtful whether it be still alive, it is to be baptized under the condition: "If thou art alive". Physicians, mothers, and midwives ought to be reminded of the grave obligation of administering baptism under these circumstances. It is to be borne in mind that according to the prevailing opinion among the learned[In 1907 -kjj], the fetus is animated by a human soul from the very beginning of its conception. In cases of delivery where the issue is a mass that is not certainly animated by human life, it is to be baptized conditionally: "If thou art a man."
I would hope these instructions are still given to Catholic doctors and nurses, though considering present indifference towards baptism, I am not sure that instruction is likely.