The presence of bacterial vaginosis or BV during the first trimester of pregnancy doubles the likelihood of a miscarriage by the end of the second trimester, researchers report.

BV - vaginal inflammation caused by the bacterium Gardnerella vaginalis - is known to increase the chances of preterm delivery. To investigate any miscarriage risk, Dr. Deborah B. Nelson of Temple University and her associates followed 1916 women who had their first prenatal visit at the Hospital of the University of Pennsylvania. All the women were in the first trimester of pregnancy, at an average of 10 weeks’ gestation.

They were screened for BV and 40 percent (757 women) had a positive result, the team reports in the medical journal Fertility and Sterility.

Women with the highest level of vaginal bacteria were 2.49-times more likely to have a pregnancy loss by 20 weeks’ gestation than those with the lowest levels.

“Clinically, this means that in addition to preterm birth, high levels of BV are also related to risk of miscarriage among women without a history of multiple miscarriages,” Nelson told Reuters Health.

“We don’t routinely screen for BV in pregnancy among low-risk women,” she explained, because oral treatment does not seem to be effective for reducing the risk of preterm delivery. “We don’t know if oral treatment is effective in reducing risk of miscarriage among women with high levels of BV during pregnancy.”

There could be a benefit of screening for BV in the first trimester and treating it to reduce the risk of miscarriage, Nelson suggested, particularly since early treatment for BV may reduce the subsequent inflammation, which may be the true risk factors for increased preterm delivery and/or miscarriage among pregnant women with BV.

SOURCE: Fertility and Sterility, November 2007.