If one miscarries at home at six weeks is there a problem of tumas meis? If so, what should one do if one lives in an apartment building where a kohen also lives
If there is anything aside from blood, a kohen should avoid becoming tamei. If there are kohanim in the building the miscarriage should be removed from the building as quickly as possible.
The Noda Beyehuda Y:D 97 is stringent for a pregnancy that grows more than 40 days, that kohanim need to avoid tumah from it. See PIschei Tshuva Y:D 369:4.
However many miscarriages after 40 days from the mikva, really stopped developing much earlier and have no status of Tumas Meis. If there is an developed tissue or the like, a kohen should avoid tumah.