Genital Infection Linked to Miscarriage

From the WebMD Archives

Dec. 5, 2002 -- A common genital infection appears to be linked to an increased risk of pregnancy loss early in the second trimester, researchers in the U.K. report. The findings suggest that screening and treating women early in pregnancy could help lower their risk of miscarriage.

The U.K. study found that women with bacterial vaginosis were more than three times as likely as women who were not infected to have pregnancy losses during the first weeks of their second trimester. In an earlier study, researcher Phillip Hay, MDBS, and colleagues found that the infection was associated with a five-fold greater risk of miscarriage in women who were 16 to 24 weeks pregnant.

"We knew this infection increased the risk of miscarriage later in pregnancy, but this new research suggests it also plays a role early in the second trimester," Hay tells WebMD.

Bacterial vaginosis is the most common genital infection among women of reproductive age. The CDC estimates that as many as 16% of pregnant women have the infection, brought on by an imbalance in the bacteria normally found in the vagina. Although having a new sex partner or multiple partners increase the chances of becoming infected, it is not clear what role sexual activity plays in the infection.

In their latest study, published in the Dec. 7 British Medical Journal, Hay and colleagues tested for bacterial vaginosis in 1,200 women who were less than 10 weeks pregnant. A total of 121 women miscarried before their sixteenth week of pregnancy. No significant association was seen between bacterial vaginosis infection and miscarriage during the first trimester, but infection was associated with a 3.5-fold increase in miscarriage risk during weeks 13-15.

Hay tells WebMD that more studies are needed to determine the impact of treating women for bacterial vaginosis early in pregnancy. The infection is generally treated with the antimicrobial drugs metronidazole or clindamycin.

A recent National Institutes of Health study found that treatment for another vaginal infection, trichomoniasis, with metronidazole might do more harm than good in pregnant women. Trichomoniasis, like bacterial vaginosis, has been shown to increase the risk of giving birth prematurely.


In that study, researcher Mark Klebanoff, MD, noted that twice as many women in the treatment group gave birth prematurely compared to a similar group of untreated pregnant women. He concluded that treatment did not improve pregnancy outcome among infected women, and may have actually been detrimental.

Hay says the NIH researchers may have treated women too late in pregnancy. He adds that his own unpublished research appears to show a benefit for early treatment.

"Our findings suggest that we need well designed treatment studies to determine whether early intervention makes a difference," he says.

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SOURCES: British Medical Journal, Dec. 7, 2002 • Phillip Hay, MDBS, FRCP, senior lecturer, department of genitourinary medicine, St. George's Hospital Medical School, London, UK • Mark Klebanoff, MD, director of the National Institute of Child Health and Human Development's Division of Epidemiology, Statistics, and Prevention Research.
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