THURSDAY, July 30, 2009 (HealthDay News) -- Women who are prone to the common vaginal infection, bacterial vaginosis, are less likely to have a recurrence if they take hormonal contraception, whether it be birth control pills or Depo-Provera injections, new research suggests.
In the study, researchers examined medical records for 330 women with a mean age of nearly 25 who visited two sexually transmitted disease clinics in Baltimore between April 2005 and October 2006. About 133, or 40.3 percent, were diagnosed with bacterial vaginosis.
The women were prescribed a contraceptive, either progestin only (such as Depo-Provera) or estrogen-progestin combination (a birth control pill).
Women who were taking an oral contraceptive that included estrogen and progestin were 34 percent less likely to have a recurrence of bacterial vaginosis than women not taking a contraceptive. Women who were on a progestin-only contraceptive were 58 percent less likely to have a recurrence, the researchers found.
Though the reduction attributed to the combined pill was not statistically significant, "it's fair to say a benefit is suggested," said senior study author Dr. Emily Erbelding, an associate professor of medicine at Johns Hopkins Bayview Medical Center.
The study appears in the July issue of Contraception: An International Reproductive Health Journal.
The study authors said they would not recommend that women who are prone to bacterial vaginosis start taking birth control for the sole purpose of warding off bacterial vaginosis.
"If you have other reasons for choosing birth control, it could be an added benefit," Erbelding said.
Dr. Jennifer Wu, an obstetrician-gynecologist at Lenox Hill Hospital in New York City, called the findings "encouraging."
"It supports that birth control pills possibly have additional advantages that can be used for treating bacterial vaginosis," Wu said.
Bacterial vaginosis occurs when the normal bacterial flora of the vagina is disrupted and replaced by an overproduction of other types of bacteria. Symptoms include a fishy odor and discharge, as well as itching, burning or pain. Women can also have bacterial vaginosis without symptoms.
It's the most common vaginal infection in women of childbearing age and is associated with preterm delivery and low birth weight babies, according to the U.S. Centers for Disease Control and Prevention.
Though treatable by antibiotics, bacterial vaginosis tends to recur, Erbelding said.
Previous research has shown that 15 percent to 30 percent of women have symptomatic bacterial vaginosis within three months after taking antibiotics, and 70 percent have a recurrence within nine months.
"As a clinician, we are always frustrated by the fact that our treatments aren't very good," Erbelding said. "They may ameliorate the symptoms for some time, but often bacterial vaginosis recurs."
Racial minorities are at greater risk of bacterial vaginosis, Erbelding said. In the study, about 82 percent of participants were black and 69 percent had been diagnosed with bacterial vaginosis before.
Bacterial vaginosis is also associated with sexual activity, douching and sexually transmitted diseases, including chlamydia, gonorrhea, herpes simplex virus and HIV.
Researchers aren't sure if bacterial vaginosis makes a woman more susceptible to the other infections or if the other infections make vaginosis more likely, Erbelding said.
"Nobody really knows which comes first," Erbelding said.
Hormonal contraceptives may help ward off a recurrence by altering the vaginal ecology or by reducing menstruation, which is also associated with changes to vaginal bacteria levels, according to the study.
The U.S. Centers for Disease Control and Prevention has more on bacterial vaginosis.