Scientists estimate that, annually in the United States, 80,000 preterm births occur related to the pregnant woman having BV, a bacterial infection in the vagina. BV results from the overgrowth of certain bacteria that are usually present at low levels in the vagina. Understanding how the body’s natural defenses work against BV may help to reduce the number of pregnant women with BV.
Researchers supported by the Pregnancy and Perinatology Branch studied a group of 126 pregnant women who self-collected vaginal swabs at two time points during their pregnancies. The swabs were analyzed for the bacteria known to cause BV and for levels of defensins, chemicals that the body produces to protect itself from infection.
Scientists discovered that levels of a particular defensin called HBD3 were lower in the pregnant women who either had BV or had greater numbers of some bacteria known to cause BV. Women with lower HBD3 levels could be at greater risk for BV due to lower levels of protective defensins. Or, it could be that the BV bacteria themselves are suppressing the body’s immune response.
Understanding how BV takes hold could help researchers develop new strategies to prevent these infections (PMID: 23174285).