I agree with the authors initial comments that despite various scientific inquiries into interventions to reduce poor pregnancy outcomes (preterm birth (PTB) and low birth weight), the issue continues to be unresolved.1 One reason for this is that PTB and low birth weight have multiple risk factors (maternal race/ethnicity, poverty, underweight, tobacco use and maternal infection), many of which occur in combination thus complicating preventive strategies.

However, it is important that the authors consider two different points when discussing periodontal disease and adverse pregnancy outcomes. Firstly, whether there is an association between periodontal disease and poor birth outcomes, and secondly whether periodontal treatment can reduce the incidence of adverse pregnancy outcomes.

Regarding the first point, we know from current evidence2 that periodontal disease is associated with adverse pregnancy outcomes although the exact causal relationship has not been confirmed. This point is reiterated in the meta-analysis highlighted by the authors:3'periodontal disease is associated with an increased risk of preterm birth and a causal relationship may exist'. Adding to the growing evidence is the recent case study involving a pregnant woman with severe gingivitis, which reported the first documented case of a stillbirth caused by oral bacteria.4

The second point regarding whether periodontal treatment can improve pregnancy outcomes is controversial with trials showing varying results in recent years. As the authors have highlighted, two recent systematic reviews3,5 on this topic have shown conflicting results. I agree with the authors that the differences reported can be explained by the different strategies employed in the meta-analysis. Polyzos et al. conducted the review by analysing the high- and low-quality trials separately while George et al. pooled all the trails together. This is a potential limitation of George et al. study and the study authors acknowledge that moderate heterogeneity was observed between the studies.

Another important difference to note is the inclusion criteria used in the two reviews. While the inclusion criteria for George et al. was that the control group should not have received any periodontal treatment, Polyzos et al. included trials where the control group received superficial oral prophylaxis treatment.6 Clubbing Macones et al. with the remaining 10 trials where the control group did not receive any sort of dental treatment may have impacted on the results and is a potential limitation of the study.

Nevertheless, despite conflicting results, both George et al. and Polyzos et al. agree that advocating periodontal treatment for the sake of improving pregnancy outcomes is not warranted. Thus, I agree with the author that based on the latest evidence periodontal treatment will not improve pregnancy outcomes. However, I do not agree that this is the end of the debate on this topic as there are still areas that need to be further addressed, namely:

1. Exploring whether treating pregnant women at the onset of gum diseases (gingivitis) will improve pregnancy outcomes. George et al.'s review showed that periodontal treatment was more effective in reducing PTB in patients with less severe periodontal disease.

2. Exploring whether elimination of periodontal disease and not just improvement will reduce adverse pregnancy outcomes. This issue was highlighted in Polyzos et al.'s review.

3. Exploring whether treating periodontal disease before conception may improve perinatal outcomes. This is especially relevant considering new research is suggesting that gum disease and poor oral health may reduce fertility in women.7

4. The need for a consensus on the definition of periodontal disease to ensure consistency in any future trials in this area.

References