The third chapter disabuses the reader of the idea that abortion has always been about the presentist concept of the "humanity" of the fetus, its moral status. (pp. 86-87) Baker shows that this paradigm resulted from the recent, nineteenth-century moral revolution of doctors based on the biomedical idea of "the continuous development of the fetus as an independent human being" (p. 109) that became the driver of a campaign to change social mores and the law. This campaign, and not religions opposed to abortion, worked: "the sinless, guiltless, and legally tolerated practice of prequickening abortion was replaced by an incompatible alternative conception of abortion as a sinful, guilt-ridden, illegal act of homicide." (p. 113)
While there was a shift in the nineteenth century, due to the increasing realization that the transitions expected by prior biological explanations were not supported by the actual evidence of development in the womb, and (not having read Baker's book) I don't know what further argument is being assumed or whether it qualifies the portion quoted at the end, what is here stated in the review is not quite correct. First, outside of some very limited jurisdictions, there is no definite category of "prequickening"; different legal systems seem to have different cut-offs for different reasons. A common one, for instance, was presumed formation, which is the forerunner of the from-conception view. The reason for this is that prior to the nineteenth century development in the womb was considered a very messy 'cooking' process -- pretty much literally, since the common view was that pregnancy was the mother's body heating the materials so that they would take shape -- and thus there were no sharp, definitive lines. The notion that 'quickening', i.e., the point at which the baby starts to move and kick, was some fundamental component of reasoning about these matters is entirely a myth; it was one kind of thing of which some laws sometimes took notice as a convenient reference point, and that's about it. Second, in a number of situations, the standard way of handling it was not blanket penalizing of abortion but penalizing particular kinds of acts directly associated with it, like the use of certain drugs, so the lack of a direct category does not always indicate that it was treated as permissible.
But more importantly, abortion prior to these cut-offs was not generally regarded as "sinless" and "guiltless", and whether it was "legally tolerated" seems largely to have depended on legal reasoning that had very little directly to do with the ethics of it. It was widely regarded as a sin and often regarded as a crime; whether it was punished depended on kinds of punishment available and assessments of general enforceability. It was generally considered to be less punishable than homicide in a proper sense; Penitentials regularly required penance for it, but the penance before the cut-off was lighter than after it. As it was often considered a religious crime, it would often have been punished by penance in an ecclesiastical court rather than by physical punishment in a royal court, which wouldn't necessarily have been seen as having jurisdiction. If you really want to talk about quickening, English common law seems to have regarded pre-quickening abortion as a serious misdemeanor and post-quickening as homicide or related to it, for several centuries prior to the nineteenth century; the reason for the difference seems not to have been biological but legal. Modern centralized states have tended to treat themselves as having universal and unlimited jurisdiction, but this is not true of legal systems in general. Murder in England and many other places was regarded as a crime against someone specifically under the King's protection (or some equivalent to that); the conditions for when penalties against murder would apply depended on when someone was taken to have entered that protection. It wasn't a statement about the nature of those outside of that protection; outlaws were outside the King's protection, for instance, but that didn't make them nonhuman.
It's worth noting as well that the shift in views in the nineteenth century also went along with extending legal protections for children. Because children were often not considered as falling within the scope of laws except where public order or religious duty were directly involved, they had very minimal legal protections; the laws didn't have them much in view, and even when it did, it was only insofar as was needed for other purposes. That's where we get the notion of 'minors', except we extend massively greater protections to minors than the law has historically done. It's not an accident, though, that the nineteenth century became stricter on abortion at the same time it started expanding legal protections for children; they were both motivated by legal rationalism that did not like arbitrary lines, and an expansion of state authority into areas it had not previously ventured much, and a concern to protect the vulnerable from suffering. But (as has been noted by more than a few people) laws actively applied over a long-enough time become part of the general moral standard, so the legal shift resulted in legal ideas, or at least popular conceptions of legal ideas, that became part of the background apparatus people used to navigate the ethics of these kinds of cases.
