Periodontal Disease and Pregnancy Risks

I don't understand why Dr. Fahey's group¹ thought their patient population would have different outcomes from the University of Pennsylvania's multisite study² concluding there is no association between periodontal health and adverse pregnancy outcomes. Treatment doesn't help either, as 3 large multisite randomized controlled trials^3-5 also showed no reduction in adverse pregnancy outcomes between experimental and controlled groups. The article's list of references includes systematic reviews concluding periodontal care does not reduce adverse pregnancy outcomes and the Polyzos et al⁶ systematic review notes differences in outcomes when "good, well designed studies" are compared to studies with poor designs.

Response from the Author

Thank you for your inquiry. At the time our study¹ was conceived in 2004, we had reviewed several small studies postulating a relationship between preterm birth, low-birth-weight infants and periodontal disease. The evidence at that time was intriguing and biological plausibility was also striking. Having reviewed the available literature prior to conducting our study, it was evident that there were both positive and negative studies published, with slight favour to positive studies showing a relationship between preterm and low-birth-weight infants and periodontal disease. Having not unveiled any Canadian studies during our literature search we were interested to know if a relationship could be replicated in our population.

Over the course of our data collection, analysis and write-up, a large amount of data continued to be published in the area. By the time we were ready to submit our study for peer review, a number of large randomized studies and meta-analyses had been published outlining the results you summarize in your letter.

Despite your conclusion that there is no evidence to support a relationship between periodontal disease and adverse obstetrical outcomes, there remains a vast amount of literature supporting the relationship between periodontal disease and chronic medical illness (diabetes, hypertension, cardiovascular disease, etc.). This literature is so well supported, it becomes an obvious question to ask—why would there not be a relationship between periodontal disease and adverse obstetrical outcomes? Hence, our dilemma with the current literature is posed to the periodontists: do we lack evidence of adverse effects in obstetrics because the tool for measuring periodontal disease in pregnancy is inadequate and therefore the relationship to adverse obstetrical outcomes cannot be demonstrated? We hope thoughtfulness and ongoing research toward a better understanding of periodontal disease in obstetrics continues.