By David A. Albert, D.D.S., M.P.H.
Columbia University College of Dental Medicine

Each year, about 12% of babies born in the United States enter the world prematurely. These "preterm" infants are born before the 37th week of pregnancy. Many have low birth weight, defined as less than 2,500 grams (about 5.5 pounds).

Preterm birth often leads to significant problems. Low birth weight babies are more likely to die soon after birth. Those who survive have a higher risk of cerebral palsy and problems with breathing, behavior, development and learning.

Researchers have been trying for many years to figure out why preterm births occur, and how to prevent them. Statistics show that certain factors increase the risk of preterm birth:

• Being pregnant with more than one baby
• Having a history of premature birth
• Having an abnormal cervix or uterus
• Having an infection during pregnancy
• Smoking or using illicit drugs
• Receiving little or no prenatal care
• Being underweight

Some studies have suggested that periodontal infections may increase the risk of preterm birth and low birth weight. Periodontal disease is an infection that damages the gums and other structures that support the teeth. The inflammation produced by infections (including periodontal infections) may be one reason for the early rupture of the birth membranes ("water breaking") and preterm birth.

More than a dozen studies have shown that women with periodontal disease are more likely to have premature babies. Only a few studies have looked at whether treating periodontal disease in pregnant women reduces their risk of premature birth.

A recent study carried out in four states (Mississippi, New York, Kentucky and Minnesota) did examine the effects of treating periodontal disease during pregnancy. In this study, treatment did not improve birth outcomes.

Does this study mean that periodontal disease is not a factor leading to preterm birth and low birth weight babies? No, one study is not sufficient to establish that there is or is not a direct link between gum disease and birth outcomes.

Three other studies of this type have already been done. Two of them found that pregnant women who got periodontal treatment had a lower risk of preterm birth. One study did not find that treatment helped.

The four-state study provided care during pregnancy. It is possible that treatment started in pregnancy comes too late. It may be necessary to treat periodontal disease before a woman conceives to prevent any pregnancy problems. Future studies should examine if earlier periodontal treatment improves birth outcomes.

The investigators in the four-state study did find a pattern suggesting that periodontal treatment might help reduce the risks of stillbirths and miscarriages.

It is too early to say that periodontal disease is a cause of poor birth outcomes. Other, larger studies need to be done.

What should a woman of childbearing age who is contemplating pregnancy do? My recommendation is to maintain good oral health, particularly periodontal health.

Good oral health is important, whether or not it affects the outcome of pregnancy. In fact, women with healthier mouths have been shown to have children with healthier mouths as well. That by itself is a good reason to treat tooth decay and periodontal disease as early as possible.

David A. Albert, D.D.S., M.P.H., is an associate professor and associate director of community health at the Columbia University College of Dental Medicine. He also holds an appointment in the Joseph Mailman School of Public Health at Columbia University. He maintains a practice within the ambulatory care network of the Columbia DentCare program in the community of Washington Heights/Inwood in Northern Manhattan.