I have been wondering recently about the possibility of a connection between heavy metals and some miscarriages. I've read that metals can interfere in pregnancy and can poison an unborn fetus with unpredictable consequences.
I was just wondering if metals may be a problem in your case. Mercury and lead are common poisonous metals. Silver fillings, old paint and old pipes are common sources, although there are other metals and other sources.
If you haven't done so already, I suggest some research in that direction, especially before you try again to have a baby (assuming you plan to).