TORONTO - There's an old saying that mothers "lose a tooth for every baby." While the tooth-loss bit may be merely folklore, it's true that pregnancy can affect a woman's oral health, including exacerbating existing gum disease.
But contrary to another long-held suspicion, a major new study has found that treating pregnant women for periodontal disease does not lower their risk of premature birth or other fetal complications.
"Numerous studies have shown an association between periodontal disease in pregnant women and adverse pregnancy outcomes, which include premature deliveries, obstetric complications like pre-eclampsia and fetal growth restriction," said Dr. Steven Offenbacher, a professor of periodontal medicine at the University of North Carolina and principal investigator of the study.
"And in particular, mothers who showed disease progression during pregnancy - and about one in four mothers get quite a bit worse during pregnancy - are seen to be at the highest risk," he said Thursday from Chapel Hill, N.C.
Gum, or periodontal, disease is caused by a bacterial infection that attacks the teeth-supporting tissues below the gum line. Left untreated, it can lead to the loss of teeth and underlying bone. Standard treatment involves scaling and root planing to remove bacteria-induced deposits (calculus and plaque) from the surfaces of teeth.
The study of 1,800 pregnant women with periodontal disease, the largest of its type ever conducted, assigned half of participants to have treatment before 23 weeks' gestation, while the remainder had no treatment.
"We found that mothers who had a scaling and root planing to treat their periodontal disease did not have reduced risk of pre-term delivery," Offenbacher said. "This would suggest that scaling and root planing, although it may improve the periodontal health of the mothers, has no effect on pregnancy outcome. Dead stop."
The study, conducted at the University or North Carolina and three other U.S. academic centres, also found that treatment in many of the mothers-to-be did not arrest progression of their gum disease.
"In the untreated mothers, 40 per cent got significantly worse," Offenbacher said. "And in the treated group, 30 per cent of them got significantly worse."
"I think at this point we don't really know the best way to treat periodontal disease in pregnant women, because we're still having a lot of disease progression."
However, that doesn't mean that pregnant women with gum disease should put off having their teeth and gums checked, and having treatment as needed, said co-author Dr. Amy Murtha, director of obstetrics research at Duke University Medical Center in Durham, N.C.
"Our study emphasizes that treating periodontal disease during pregnancy is safe, but that standard periodontal care is not enough," Murtha, who presented the findings Thursday at the annual meeting of the Society for Maternal-Fetal Medicine in San Diego, said in a release.
It's possible, the researchers suggest, that pregnant women may need more aggressive treatment for gum disease, beyond the standard care provided in the study, to bring down the rate of premature delivery.
Murtha said much remains unknown about the link between gum disease and the increased risk for pre-term birth and low-weight babies.
"Periodontal disease and poor pregnancy outcomes travel together, but we don't know why."
Offenbacher said changes in hormone levels and a somewhat lowered immune response may allow oral bacteria to flourish and exaggerate the body's inflammatory response. But he said more studies are needed to fully explain the connection.
Commenting on the U.S. study, Dr. Benoit Soucy of the Canadian Dental Association said the findings are not surprising because the association between pregnancy and gum disease is "a very, very complex issue."
"The reason they're not surprising to us is that there is no mechanism that has been identified to link periodontal disease to premature birth or small birth weight," Soucy, the association's director of clinical scientific affairs, said from Ottawa.
"There could be there is an underlying process that is masked by other factors, and that is very likely because periodontal disease is extremely common. According to the best numbers that we have ... there would be as much as 70 per cent of the population that is affected by periodontal disease at one time or another."
Any woman who is considering getting pregnant should have a dental exam and regular monitoring during pregnancy because of the bumped-up risk for either developing gum problems or making existing disease even worse, he said.
"There is no good general health if your mouth is not healthy. It is very important no matter what to keep your mouth in good health."
