Common Treatment to Prevent Recurrent Miscarriage Doesn't Work

From the WebMD Archives

Nov. 16, 1999 (Minneapolis) -- A widely used form of immunotherapy does not protect against recurrent miscarriage and in fact may increase the risk of pregnancy loss, according to a study in a recent issue of The Lancet. In the study, the controversial procedure -- called mononuclear-cell immunization -- had no benefit over placebo. Therefore, this therapy "should not be offered as a treatment for pregnancy loss," the authors write.

Most women who have miscarriages have one or two; however, about 1% of couples experience three or more. Although the cause is usually unknown, some investigators have suggested that the pregnant women may have an immune-system defect that causes their bodies to "reject" the fetus through miscarriage.

In a healthy pregnancy, the mother develops immune-system responses that allow the pregnancy to continue. If this doesn't happen, the mother's body perceives the fetus as foreign material and rejects it -- a phenomenon known as recurrent miscarriage. Without medical intervention, this will continue to happen with each new pregnancy.

To prevent recurrent miscarriage, mononuclear-cell immunization is offered by many medical centers in the U.S. and around the world. With this therapy, the mother is immunized with white blood cells from the baby's father, on the theory that this immunization will "override" the mother's own immune response to the pregnancy. However, the effectiveness of this technique has been in question due to conflicting results of clinical studies. The findings of the reported study support the opinion that mononuclear-cell immunization doesn't work.

"These findings should finally put closure to a very controversial treatment for recurrent miscarriage," researcher Carole Ober, PhD, tells WebMD. "The treatment is not effective. ... However, the good news is that the success rate was quite good in the control group -- 65% among women who became pregnant. This is great news for couples with recurrent miscarriage and confirms the impression of many that there isn't anything wrong in most couples with unexplained recurrent miscarriage. With the appropriate medical and emotional support, most of these couples will have a baby in their next pregnancy."

Of the 183 women in the randomized study -- designed to test the effectiveness of paternal mononuclear-cell immunization -- 91 were assigned to the treatment group; 92 were assigned to the placebo group and received sterile saline. All the women had had at least three miscarriages of unknown cause.

The women were followed for 12 months. Failure of treatment was defined as either the inability to become pregnant within the study period or a pregnancy loss before 28 weeks of gestation. Successful treatment was defined as a pregnancy of 28 or more weeks of gestation. The study included two analyses: one consisted of all women, and the other consisted only of women who became pregnant.

Of the 171 women who completed the study, 36% of the treated participants met with success, compared with 48% of the controls -- roughly indicating that no treatment was better than the treatment studied. This trend continued among women who became pregnant: 46% of the treatment group sustained their pregnancies compared with 65% of the control group.

"Our final sample was smaller than we had originally planned," Ober tells WebMD. "However, the pregnancy loss rates were so much higher in the treated group that, even had we been able to continue to recruit more subjects, the best we could have hoped for was no difference between the groups." Instead, a significantly higher rate of success was found in the control group.

"This study was very well done, by being placebo-controlled, and serves as a model for other studies," Sandra Carson, MD, tells WebMD. "All of our studies on spontaneous abortion need to be done just like this." Carson, an infertility specialist and a professor of obstetrics and gynecology at Baylor College of Medicine in Houston, was contacted by WebMD for comment and was not involved in the study.