It occurs to me that nothing I have read about NFP take into account the decline in rates of death in childbirth. That is, I realized that in another century and even in the present in other parts of the world, it is very possible, and even probable that Mrs. K-G would have died trying to give birth to the Lad, and might be suffering a fatal infection right now from the second birth had she survived the first. Even if she did survive both, there's a very good chance she would have wound up permanently unable to bear more children. Some female bodies are not especially suited to pregnancy and childbirth. It would seem that a concept like NFP ought at least to address these facts, before the (invariably healthy and menstrually regular) authors cheerfully tell such women that this just their cross to bear, and that thanks to the wonders of modern science they can now bear it over and over again...