What is the ruling of Islamic law concerning a fetus born dead in the fifth month and buried without ghusl (ritual washing), shrouding, or prayer? Is expiation incumbent upon the one who did that?

This action contains several prohibitions: burying a miscarriage in non-Muslim cemeteries, and not washing, shrouding, or praying over it. The one who did this must repent, and there is no need to exhume the grave because it is too late and the body has decomposed. No expiation is required from the doer except repentance, for "indeed, good deeds do away with ill deeds."