The Quest for the Ideal Tests to Predict Preterm Births

From the WebMD Archives

Feb. 8, 2000 (Miami) -- Preterm delivery has been one of the biggest dilemmas in obstetrics, resulting in illness or death of many infants. One problem is being able to predict which women will go into labor and deliver before term, or before 37 completed weeks of pregnancy. Another problem is being able to effectively treat the women with medications or other therapy. Recent studies are showing that simple, safe, and noninvasive tests can often be used to predict preterm births, but they are often only a first step. In order to be really valuable, the tests need to be combined with methods to prevent premature births, which is still the next, most important, step.

Research into simple, safe, and noninvasive tests to predict preterm birth was the topic of two presentations given here last week at a meeting of maternal/fetal medicine specialists. A co-author of one of the studies says the information already serves a purpose, though, by helping physicians better understand the warning signs for preterm births.

Inflammation is an important part of disease in pregnancy, explains Roberto Romero, MD. "All of these presentations are saying that an inflammatory reaction can be detected locally in vaginal/cervical secretions or in maternal blood," Romero tells WebMD. Romero is chief of the perinatology research branch of the National Institute of Child Health and Human Development (NICHD) and a professor or obstetrics and gynecology at Wayne State University in Detroit.

"We are [attempting] prediction, and we hope that prediction will [ultimately] help us with prevention," says Romero. He says the next step is to confirm these observations, determine the best time for screening, and then use that information to see if a way can be found to halt the process of premature deliveries.

One presenter, Robert L. Goldenberg, MD, agrees, saying the tests are useful for further study, but he'd wait before putting them into practice. "[Our] data clearly show that it's possible to use a group of tests to better predict preterm birth than any single test," he tells WebMD. "I think the most important thing is to develop interventions using the tests," he says.

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There is one possible exception, he says. A negative result from a test for fetal fibronectin is a strong indicator of a low risk of preterm birth, which could certainly change how a pregnant woman's doctor manages her care and whether she would be managed in or out of the hospital. Goldenberg is a professor of obstetrics and gynecology at the University of Alabama School of Medicine, in Birmingham. He made his presentations on behalf of the Maternal Fetal Medicine Unit Network of the NICHD.

Goldberg's study sample was based on a healthy group of almost 3,000 pregnant women with no symptoms of preterm birth. The investigators then compared women who had a spontaneous preterm birth (SPB) before 32 weeks and before 35 weeks to this group. The goal was to check the ability of a single test or combination of tests to predict SPBs. The tests were administered during the 22nd to 24th weeks of pregnancy. Analysis of the data revealed significant associations between SPB at both 32 weeks and 35 weeks, with an array of warning signs such as a positive fetal fibronectin test, short cervical length of the mother, and blood levels of other chemical factors.

The researchers found a low effectiveness of individual tests to predict SPB, but when multiple tests were used, the sum was greater than the parts. This indicates that the tests generally provide additive information with respect to each other, and that developing a test combining multiple markers for SPB is feasible.

He also said there is a need for further studies of several different combinations of tests to determine their predictive value. These combined tests are not being used in doctors' practices at this time. Until there is a test that can be done in the office or hospital to predict preterm birth, it is generally recommended that pregnant women report to their doctors any preterm discomfort or hardening of the uterus or abdomen, uterine cramping, back ache, thigh ache, and vaginal discharge or bleeding.

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