Amniotic Fluid Test May Predict Premature Birth Risk

First screening tool could be available within three years, researcher says

THURSDAY, Feb. 10, 2005 (HealthDay News) -- For the first time, researchers have mapped biochemical substances called metabolites in amniotic fluid, and that finding has yielded important clues to determining which women who experience preterm labor are also at risk for delivering prematurely.

The news, announced Thursday at the 25th annual Society for Maternal-Fetal Medicine meeting in Reno, Nev., marks a potential new advance in the management of pregnant women who go into preterm labor. Clinicians one day may be able to perform simple tests to predict which women will deliver at term and which ones will require aggressive treatment to delay their delivery.

"In terms of [patient] management, this is potentially a big step forward," said Dr. Nancy S. Green, medical director of the March of Dimes. "Now you can't separate these groups, and so everyone gets treated more aggressively."

This type of diagnostic advance could also help reduce the nation's rate of preterm birth, a leading cause of infant mortality and long-term disability. Almost one in eight babies in the United States is born prematurely before 37 weeks of gestation, according to the March of Dimes.

"What I don't want to say is that we will have these sorts of tests available for women tomorrow," cautioned Dr. Roberto Romero, chief of the perinatology research branch of the National Institute of Child Health and Human Development and lead author of the study.

Still, Romero expects at least one test, for detecting intra-amniotic inflammation -- a risk factor for preterm delivery -- to be available in about two to three years.

If the results are confirmed, "this could add another arrow to our diagnostic quiver," said Dr. Charles J. Lockwood, chairman of the Department of Obstetrics and Gynecology at Yale University School of Medicine.

Still, the medical community and mothers-to-be may not want to get their hopes up just yet.

Lockwood said there have been a growing number of studies attempting to discern patterns of protein and metabolite expression in various disease processes. But attempts at replicating initially exciting results have almost universally failed, he cautioned. That may be due to shortfalls with current statistical modeling.

Difficulties arise when looking at a new set of data from a different population of patients, he explained. "The problem is that like a fingerprint, the data is unique to that group of patients and cannot be extended to a second population who also has a unique collective fingerprint."

Even if a diagnostic tool were developed for use within medical facilities, it would involve amniocentesis, an invasive procedure that is unlikely to be widely employed clinically, Lockwood maintained.

For this study, Romero and an international team of researchers performed biochemical analyses of the amniotic fluid of 55 women who experienced preterm labor. One group delivered at term, another group had inflammation and delivered prematurely, and the third group had no inflammation but also delivered prematurely.

Using metabolic profiling, the researchers were able to correctly identify which women delivered at term and which delivered prematurely -- with or without inflammation -- with 96 percent accuracy.

Romero said a second study involving a larger number of women has confirmed the effectiveness of the method. The next step, he said, is to complete studies in different groups of patients this year.

And in two to three years, clinicians may have a test for biochemical markers of intra-amniotic inflammation that is simple, quick and highly sensitive, Romero said.

In another study presented at the same meeting, researchers from the Mayo Clinic and Medical University of South Carolina found that the large majority of expectant mothers treated with drugs to prevent preterm labor do go on to deliver at or near term.

Of 154 expectant mothers treated for preterm labor who still had not delivered one week later, more than 87 percent went on to deliver their babies after 34 weeks. At that point in pregnancy, standard practice is to deliver the baby rather than treat the mother once more if she goes into labor, the researchers said.

More information

For more on treating preterm labor, visit the March of Dimes.

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