A grant to the University’s School of Dentistry will fund research to determine if a direct relationship exists between gum disease in pregnant women and preterm births and low birth weight.

Previous research has already shown an association between the two, and the three-year study funded by a $7.5 million grant from the National Institute of Dental and Craniofacial Research will examine whether there is a direct causal relationship.

Bryan Michalowicz, a preventive sciences professor, said if the study finds a direct connection, it could have a profound impact on prenatal care and health care.

He said the rate for preterm labor among women with gum disease is double that among women with healthy gums. The centers participating in the study will focus on women from that are at a high risk for preterm birth.

In the study, women with gum disease will be randomly sorted into two groups. Those in the test group will receive nonsurgical treatment for their gum disease during the pregnancy’s second trimester.

One theory regarding the possible link is that the bacteria related to gum disease access the bloodstream through the mouth. Once a significant amount is present in the blood, the bacteria travel to the birth membranes and amniotic fluid.

Once there, they elicit an immune system response – the release of inflammatory mediators – an effect of which is smooth muscle contractions, inducing early pregnancy.

The other theory, although based on the same principles, holds that the inflammatory mediators respond to the infection in the mouth, and the mediators, not the bacteria, travel to the birth membranes and amniotic fluid causing the same effect.

Because other infections in pregnant women – such as urinary tract infections – have been related to preterm and low birth-weight babies, “it is not such a big step to speculate that oral infections can also precipitate these problems,” Michalowicz said.

Virginia Lupo, an obstetrician at Hennepin County Medical Center, one of the centers participating in the study, said the national rate for preterm birth is approximately 11 percent. At the medical center it is twice that amount.

She said she thinks the study might find that there is no direct correlation between gum disease and low birth weights. Lupo pointed out that both gum disease and poverty are associated with preterm birth, and many of the factors that lead to gum disease are associated with poverty.

These factors include having little access to health care or being less likely to seek out periodontal care, Lupo said.

The study’s results might lead future research to focus on the factors of poverty that contribute to preterm birth, she said.

“We don’t know why, but we know poverty is associated with higher preterm delivery rates,” Lupo said.

“My question, though, is whether gum disease is not another indicator of poverty,” she said.

Amos Deinard, a University pediatrician who will be on the data monitoring board for the study, agreed with Lupo’s evaluation.

“You don’t have the same incidence of gum disease, low birth weight and prematurity in white, middle- to upper-class America,” he said.

Like Lupo, Deinard stressed the variety of poverty-related factors that could contribute to preterm birth, such as drug use or poor nutrition.

But, Lupo said, even if gum disease is just one factor contributing to preterm birth, simply including it in the prenatal regimen could have an impact.

“It would be a lot cheaper to treat gum disease in a pregnant woman than to put a baby in the intensive care unit for several weeks,” she said.