I could be wrong but to me the bleeding would make getting pregnant more difficult not affect an embedded embyro.
If your progesterone levels are falling during the first weeks of pregnancy, it might be worth discussing the merits of a progesterone supplement for the first few weeks.
Also recurrent miscarriages need to be investigated.
Have you had any successful pregnancies?
Do you have problems with endometriosis?
Have you had a hsg (or hycosy is nicer) to confirm the shape of your uterus and to rule out any fibroids?
Have any tests been performed on the miscarried embryo's to look for congenital abnormalities which can lead to spontaneous termination of pregnancy?
Have you and hubby been tested for known recessive genes which if you both carry could lead to abnormalities?
Also has hubbys sperm been looked at for motility and abnormalities and your eggs?