Cats are not jealous of, nor do they sleep on the heads of
babies. They don't "smell milk on the baby's breath" and
vampire-like, suck the life out of them. This is an
Urban Legend, as disproved by a great many videos. What they do do is sleep
beside babies, especially feverish ones, to keep them warm (some
pack instinct, apparently, they'll do the same to adults and their own...). Apparently, what happened in a few cases was that
the kid died on its own, and cat thinks...cold kid, I'll warm it...Mom goes "EEK! Must have been that CAT!"
FWIW, there is a charming legend of a barn cat named Avigal who sheltered the Christ Child....UPDATE!
And the following story from alt.pets.cats: Some unknown poster had a large Norwegian Forest Cat, white in color. Another member of her immediate household had recently given birth. With all customary joking, the offspring of B was put in a crib, without a net over her. A few hours pass. "Has anyone seen the cat?" A household search was in order, ending in, yes indeed, the crib, where the oversized feline had managed to curl himself into a position completely encircling the little tyke, who was, apparently, quite taken by the, as the poster put it "ultimate cat experience" of fur/warmth/purring/etc.
Wow!