I suspect something much more sinister.
Like what? Some sort of voodoo thing? Something very similar happened some years ago, also in Chicago, but involving blacks. A rather dark, unattractive woman wanted the baby being carried by a pretty light-skinned black gal. If I remember correctly, it was the boyfriend or brother who killed the pregnant woman and cut out the baby. I don’t remember how long the baby survived, but for at least a time the ugly woman presented the baby as her own. She just wanted a pretty little baby of her own.