BV increases risk for adverse pregnancy outcomes

Pre-pregnancy visits should include vaginal examinations to rule out bacterial vaginosis (BV), as well as oral examinations to assess for periodontal disease, according to a prospective Finnish study. Both infections have been linked to adverse pregnancy outcomes.

Through newspaper ads, researchers recruited 252 healthy women who desired pregnancy and had stopped using contraception. All of the women were white and had regular menstrual cycles and were not pregnant at the time of entry. Women who had a history of preterm birth (PTB) or who had been using antibiotics within the past 2 weeks were excluded. The first 130 women to become pregnant were included in the analysis.

Medical histories were collected and both oral and gynecologic speculum examinations were conducted. Bacterial vaginosis (BV), diagnosed by vaginal swab and Gram-staining, was found in 16% (N = 21) women, and periodontal disease in 12% (N = 15) women.

Of the 130 pregnant women analyzed, 20% (N = 26) experienced an adverse pregnancy outcome: 17 women suffered a miscarriage (defined as pregnancy loss before 22 weeks’ gestation) and 9 had PTB (defined as delivery before 37 weeks’ gestation).

Both BV and periodontal disease had significant associations with adverse pregnancy outcomes when the researchers performed a univariate analysis. But upon multivariate analysis, BV had only a borderline association with adverse pregnancy outcome (OR 3.2, 95% CI 0.9-10.7, P = 0.061). Periodontal disease had a more significant link (OR 5.5, 95% CI 1.4-21.2, P = 0.014). When both infections were present, the odds ratio on multivariate analysis was 13.1 (95% CI 1.9-135.1, P=0.031).

Etiology Behind BV Link

Both BV and periodontal disease have been shown to be associated with a high bacterial burden and increased levels of pro-inflammatory cytokines and other mediators of inflammation. In the past, BV has been associated with both miscarriage and PTB, but trials of BV treatments have not been shown to effectively reduce PTB rates. Periodontal disease diagnosed during pregnancy has also been found in some studies to lead to an increased risk for low birth weight and PTB.

The researchers suggested that the mechanism behind BV’s link to poor pregnancy outcomes is related to the “ascension of virulent BV-associated pathogens to the upper genital tract.” They speculated that periodontal disease may increase the bacterial burden or qualitatively change the microflora in periodontal pockets, which then would spread.

Recommendations for Pre-pregnancy Screening

Based on their preliminary data, these researchers recommended that all women who are contemplating pregnancy be advised to have a routine dental examination as well as gynecologic examination and testing for BV. “This may ultimately have a major impact on antenatal healthcare,” they wrote, “and may be a new intervention to decrease the risk for unexplained or idiopathic adverse pregnancy outcome.”