63 But another very grave crime is to be noted, Venerable Brethren, which regards the taking of the life of the offspring hidden in the mother's womb. Some wish it to be allowed and left to the will of the father or the mother; others say it is unlawful unless there are weighty reasons which they call by the name of medical, social, or eugenic "indication." Because this matter falls under the penal laws of the state by which the destruction of the offspring begotten but unborn is forbidden, these people demand that the "indication," which in one form or another they defend, be recognized as such by the public law and in no way penalized. There are those, moreover, who ask that the public authorities provide aid for these death-dealing operations, a thing, which, sad to say, everyone knows is of very frequent occurrence in some places.
Source: Casti Connubii (Vatican.va)