A new test can predict – and, perhaps, prevent – the more than 500,000 premature births that occur in the United States annually.

Like most expectant mothers, Regina Biscoglio worries about the health of her unborn baby.

"One of the things that's most concerning is if the baby is born prematurely. There are so many potential consequences to that," Biscoglio said.

"Premature deliveries are responsible for lung problems, responsible for a whole slew of problems," said Dr. Jacques Moritz, director of gynecology at St. Lukes Roosevelt Hospital in New York.

However, a recent study shows that a procedure called the lac-test can predict premature labor by measuring levels of lactic acid in pregnant women. Athletes commonly use the lac-test to see if they are training and pushing themselves hard enough.

"In labor, the womb is contracting, and so that produces lactic acid, and that's what's picked up on this test," said Professor Philip Steer, consulting obstetrician for the British Journal of Obstetrics and Gynecology.

A woman's water breaking sooner than expected is considered a sign of imminent labor, although only a third of those women give birth prematurely.

Researchers in Sweden used the lac-test on women whose water broke early to determine which ones were in danger of premature delivery. Of the women with high lactic acid levels, 87 percent went into labor within 48 hours.

Knowing that likelihood could let doctors know when mother and baby need extra care – helping babies get a healthier start to life.

"You want to give them steroids, kind of like the strong steroids, and it turns the baby's lungs on, so that the baby will need less support to breathe," Moritz said.