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FRIDAY, Jan. 9 (HealthDayNews) -- Low blood levels of an immune system protein in early pregnancy are associated with a high risk of miscarriage, Australian researchers report.

The protein, macrophage inhibitory cytokine 1 (MIC 1), is believed to help prevent a possible immune system attack that could cause rejection of the fetus, says a report in the Jan. 10 issue of The Lancet.

If the finding is confirmed, MIC 1 testing might be used to warn of a possible miscarriage, and the molecule could be a target for miscarriage prevention treatment.

The researchers at Monash University in Melbourne and the University of New South Wales found MIC 1 levels during the first six to 13 weeks of pregnancy were about one-third lower in 100 women who went on to have miscarriages than in 200 women who delivered normally.

"It is tempting to speculate that changed production of MIC 1 in the placenta is part of the mechanism initiating spontaneous pregnancy loss," says study author Dr. Stephen Tong, a professor of obstetrics and gynecology at Monash University. "If a causal link between low MIC 1 and miscarriage is confirmed, then MIC 1, or its synthetic analogs, might be useful in prevention of miscarriage."

But that's a big "if," adds Dr. Euan M. Wallace, clinical director of the university's Centre for Women's Health Research and a member of the research team.

"The roles of MIC 1 are not known yet, and whether it is cause or effect is not clear," Wallace says. "While we are clearly excited about the results, we are very cautious about interpretation."

It's too early to consider specific methods of preventing miscarriage based on the finding, Wallace says: "We need to unravel cause or effect issues."

The research group has started a prospective study, following women through pregnancy to get more specific data on the relationship between MIC 1 levels and the risk of miscarriage, Wallace says.

A lower blood level of MIC 1 "may just be an effect of an already failing pregnancy," he says.

About 10 percent to 15 percent of all clinically confirmed pregnancies end in miscarriage, Wallace says. In many cases, the cause can be identified as abnormalities of the chromosomes, the cellular carriers of genetic material.

But "a large number of pregnancies that are chromosomally normal are still lost," the journal report says. "No treatment exists to prevent miscarriage, and there is no established predictive marker."

A blood test to measure MIC 1 levels early in pregnancy could provide such a marker, Wallace says, but its value "clearly needs confirmation by the prospective study."

More information

To learn more about miscarriage, visit the March of Dimes Birth Defects Foundation and the National Institutes of Health.

(SOURCES: Stephen Tong, M.D, professor, obstetrics and gynecology, Monash University, Melbourne, Australia; Euan M. Wallace, M.D., clinical director, Centre for Women's Health Research, Monash University, Melbourne, Australia; Jan. 10, 2004, The Lancet)

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