Recurrent miscarriages have many causes, including abnormalities in a woman's uterus and genital infections. But about half of the time, the reason for recurrent miscarriages is unknown.
Pregnancy suppresses a woman's immune system to prevent it from rejecting the fetus.
This suppression causes a drop in levels of immune-system chemicals called cytokines that regulate inflammation. But this process appears to go awry in some women who have repeated miscarriages, according to a team of researchers at the University of Vienna led by Dr. Gertrud Unfried. Previous research has detected high levels of these inflammatory cytokines in women who have had more than one miscarriage. They also looked at 91 women who had had at least two successful pregnancies. The IL-1 RA gene is involved in the production of the cytokine interleukin 1.