Rh disease seems to me to be far from being the exact same issue as what was suggested in this thread. Rh disease is due to bloodtype incompatibility between the mother and the baby, and only sometimes triggers.

Even then, Rh disease usually only causes symptoms in the baby in subsequent pregnancies with the same bloodtype incompatibilities, when the antibodies already exist in the mother.

I'm not sure what exactly it means that Neanderthal women's uterus wouldn't be able to host HS babies, but that sounds different to me.

Unless you know more about this Neanderthal uterine incompatibility.