One in 10 babies is born prematurely in this country.

Researchers had suspected 30 to 40 percent of those births are caused by genetics. Now a new study is the first to show which genes are involved.

The lead researcher on the study shared why this discovery is so important.

"So these are genes that are acting in the mom, but even more important than that is for the first time, we have an idea of what tissue in the mom is the one that's likely driving the risk for preterm birth," explained Dr. Louis Muglia, director of the Center for Prevention of Preterm Birth at Cincinnati Children’s Hospital.

Researchers identified six gene regions that link to preterm birth. They discovered cells within the lining of the uterus play a larger-than-expected role in the length of pregnancy.

Another gene area raises questions about how a lack of selenium - a micro nutrient found in nuts, leafy green vegetables, and meat - might affect women going into labor too early.

“There are parts of the world, even in the U.S., where the soil may be deficient in selenium,” said Doctor Trevor Mundel, president of the Global Health Division at the Bill and Melinda Gates Foundation.

The Bill and Melinda Gates Foundation, which helped pay for the study, says discovering the importance of selenium in pregnancy could save the lives of premature babies in developing countries.

“With this kind of work and identifying it early and having an intervention that we can practically implement can make a huge difference,” said Dr. Mundel.

The March of Dimes says knowing which genes have a connection to preterm birth will allow doctors to test pregnant women to see who's at risk. Doctors will also be able to prescribe new medications to help prevent babies from being born too soon.

“We think this is an important breakthrough in finding solutions to premature birth, which is the leading cause of death for children between ages of 0 and 5 and a leading cause of disabilities for babies,” said Stacey Stewart, president of the March of Dimes.