Is there evidence of a relationship between pre-eclampsia and periodontitis?

The review searched several databases which included Medline (from 1950), Pubmed (from 1946), Embase (from 1949), Lilacs, Cochrane Controlled Clinical Trial Register, CINAHL, ClinicalTrials.gov and Google Scholar (from 1990).

Two of the authors (LD and HN) independently assessed the eligibility of studies by looking at the titles, abstracts and methods. If there was a disagreement, a third reviewer was consultant (QA) for a decision.

A data extraction form was created and used. Data collected included: the first author's name; publication year; study design; number of cases; number of controls, total sample size; country; national income group; mean age; the risk of estimates or data used to calculate the risk estimates; confidence intervals (CI) or data used to generate CI. For assessment of socioeconomic status and its role as a possible influential factor, the World Bank classification through Gross National Income per capita was used to determine which level (low-income, lower-middle-income, upper-middle-income, high-income) a country resided in. All authors cross-checked all data and discussions were had to resolve disagreements. Statistical software 'RevMan' was used to input data. Pooled odds ratios, mean difference, and 95% CI were calculated for the association between periodontitis and pre-eclampsia using a random-effects model. A significance level of 0.05 was used for pooled effect. Forest plots for primary analysis and subgroup analysis show the raw data, odds ratio and CIs, means and SDs for the chosen effect, heterogeneity statistic (I²), total number of participants per group, overall odds ratio and mean difference. Groups were divided for subgroup analysis by: study design (case-control and cohort); the studies' definition of periodontitis (defined by pocket depth [PD] and/or clinical attachment loss [CAL]); and national income (high-income or middle-income or low-income countries). Cochran's Q statistic and I² statistic were used to determine heterogeneity and degree of heterogeneity, respectively. For publication bias, Egger's regression model and fail-safe number was used.

Thirty articles and 9650 women were included in total. Six of the studies were cohort studies (2840 participants overall) and 24 were case-control studies. Pre-eclampsia was defined the same across all studies, whereas periodontitis differed. There was a significant association between periodontitis and pre-eclampsia (OR 3.18, 95% CI 2.26-4.48, p < 0.00001). In subgroup analysis of just cohort studies, the significance increased (OR 4.19, 95% CI 2.23-7.87, p < 0.00001). It further increased looking at lower-middle-income countries (OR 6.70, 95% CI 2.61-17.19, p < 0.0001).

Periodontitis in pregnancy is a risk factor for pre-eclampsia. The data would suggest that this is more prominent in lower-middle-income subgroups. Further research could be undertaken to explore the possible mechanisms and also if prevention of adequate treatment can reduce the risk of pre-eclampsia, thereby improving maternal health outcomes.