A virus called CMV, for cytomegalovirus, is the most common cause of uterus infections, but its impact on pregnancy outcomes is not fully understood. Now, Japanese researchers have linked it to the risk of miscarriage.

Miscarriage rates in healthy women with vaginal shedding of CMV - indicating they have the infection - are significantly higher than those in comparable women without CMV infection, report Dr. Hiroyuki Tsutsumi and colleagues at Sapporo Medical University School of Medicine.

As reported in the Journal of Medical Virology, the researchers studied 993 healthy pregnant women. Vaginal shedding of CMV was determined by a test that detects viral DNA sequences, and CMV DNA was found in 76 (7.7 percent) of the subjects.

CMV-positive women were almost 7-times more likely to have a miscarriage than were CMV-negative women.

One possible underlying reason, suggest the investigators, is that CMV infection may cause excessive immune reactions between the mother and the fetus.

The team calls for further studies, but concludes that routine CMV screening during pregnancy may be useful.

SOURCE: Journal of Medical Virology, June 2006.