The infant death rate in Ireland in the 30s was well over 20%. Given a troubled population, I woudn’t be surprised that in a well-run orphanage, it wasn’t far more than that. And Ireland was hardly exceptional. You’ll note that the estimate was not gotten through sorting through the bones, but by contacting the local authorities. You’ll also note most of these children were eventually adopted.
As a Catholic, the sickening thing to me was the disposal of the bodies: the poor treatment of the bodies despite Catholic beliefs makes it very easy to believe that their souls weren’t cared for while they were alive.
The sickening thing to you should be that these women were brutalized because of being pregnant. Ostracized, abandoned, thrown away. Disgusting. All brought to you by Catholic zealots.