SRP reduces preterm birthrate

April 1, 2004
Nearly 12 percent of all infants are born preterm. To put that into perspective, 4,000,000 babies are born each year in the United States, and of those, approximately 500,000 are preterm.

by Trisha O'Hehir

Nearly 12 percent of all infants are born preterm. To put that into perspective, 4,000,000 babies are born each year in the United States, and of those, approximately 500,000 are preterm. According to the March of Dimes, delivery before 37 weeks is defined as preterm. Full-term pregnancies are usually 37 to 40 weeks.

Known risk factors for preterm births include a history of preterm delivery, a pregnancy of twins or more, tobacco, alcohol or illegal drug use, underweight or obese mother, diabetes, high blood pressure, urinary tract infections, and vaginal infections. However, these risk factors account for only a portion of the 500,000 preterm births each year. Some preterm births are still not explained by the established risk factors.

Periodontal disease is now considered a risk factor for preterm birth. Studies reveal that women with gum disease are up to seven times more likely to have a preterm birth. More conclusive evidence is needed to determine if treatment of periodontal disease will reduce the incidence of preterm delivery.

At one of the early perio-systemic link conferences, a government physician presented the case for antibiotic intervention to reduce both periodontal and vaginal infection, and therefore effectively prevent preterm births due to infection. She reasoned that taking an antibiotic would be easier and cheaper for the government to fund than dental hygiene intervention. The dental audience was stunned into silence! The logic of using a systemic antibiotic during pregnancy to accomplish what a toothbrush and dental floss could easily do was unbelievable.

Where was the logic in this? The government physician was looking only at the financial bottom line. To her, it made perfect sense to dispense antibiotics to pregnant women to treat infection, which she reasoned would reduce the number of preterm births and the resulting hospital costs. She couldn't comprehend how much easier it would be to simply prevent the periodontal infection. Those in the dental profession know that a toothbrush and floss cost far less than drugs.

Also, the government physician wanted to save money by eliminating oral hygiene instruction or periodontal therapy to pregnant women. She was confident that her solution was fiscally and scientifically sound.

The periodontal research community recognized the challenge and worked diligently to confirm the link between periodontal disease and preterm birth. They also documented the effect of both non-surgical and antibiotic intervention. The results are very interesting.

Dr. Marjorie Jeffcoat, periodontist and editor of the Journal of the American Dental Association, led her team of researchers at the University of Alabama in a pilot study that compared the effects of non-surgical therapy with and without systemic antibiotics. The research team compared four treatment options in a group of 366 pregnant women with periodontal disease who were primarily African American, average age of 23, and 13 percent were married.

One group received supragingival prophylaxis plus placebo pills. The second group received subgingival scaling, root planing and placebo pills. The third group received subgingival scaling, root planing, and the antibiotic (metronidazole). The control group received no treatment.

Periodontal disease in this study was defined as more than three test sites with attachment loss equal to or greater than three millimeters. This was evidence of early periodontal disease, not advanced.

Oral hygiene instructions, toothbrushes, dental floss, and toothpaste were given to all study subjects.

It was anticipated that the metronidazole group would have fewer preterm deliveries, but that was not the case. The preterm rate (before 37 weeks) in this group was 12.5 percent, compared to nine percent in the prophylaxis plus placebo group, and four percent in the SRP plus placebo group. The control group had a preterm delivery rate of 12.7 percent. Based on these findings, the metronidazole not only didn't help, but actually negated the positive effects of the scaling and root planing! The 12.5 percent preterm birthrate in the SPR plus metronidazole group is not clinically different than the 12.7 percent rate in the control group.

If the definition of preterm is set before 35 weeks, the numbers were 5 percent SRP plus metronidazole, 0.8 percent SRP/placebo, 3 percent prophylaxis/placebo, and 6 percent for the control group.

A 2001 study published by Dr. Mitchell-Lewis reported higher preterm birth rates for minority women in New York. In that study, scaling and root planing resulted in a preterm rate of 13.5 percent compared to 20 percent in the control group.

Dr. Jeffcoat suggests that a large study of 1,800 subjects is needed to convincingly demonstrate scaling and root planing's effectiveness in reducing the incidence of preterm birth. No metronidazole should be used in the large-scale study. Dr. Jeffcoat did not speculate how scaling and root planing reduced the preterm birth rate. That information will come with future studies.

If your pregnant patients have periodontal disease, go ahead and treat them with SRP, but avoid antibiotics. The best care is prevention — ensuring that patients are periodontally healthy before they become pregnant.

Trisha E. O'Hehir, RDH, BS, is a senior consulting editor of RDH. She is also an international speaker, author, instrument designer, inventor, and oral health detective. Her Web sites are and She can be reached at (800) 374-4290 or at [email protected].