I could possibly be 'Factor V Leiden'. My sis and I had numerous miscarriages. We found out we had a common blood disorder mentioned above, that can cause miscarriages. After finding this out, we both realized we had to take daily blood thinning meds while pregnant, injured, or after surgery. WE had to give ourselves shots in our lower stomach region while pregnant in order to carry full term.
It's a common thing, ask your doctor for more info. Also, if you heard the 'urban legend' about Cheetos causing miscarriages, I know first hand that it may possibly be true.