The most common vaginal infection for women in their reproductive years may be one you've never heard of: Bacterial vaginosis (BV), a condition that can cause an unpleasant odor and discharge, and may affect as many as 28 percent of women, according to a recent study in Obstetrics & Gynecology. It's important to seek care, since untreated BV can cause reproductive complications, says Sharon Hillier, Ph.D., professor of gynecology, obstetrics, and reproductive sciences at the University of Pittsburgh School of Medicine. Here's what you need to know:

Causes:

BV is the result of an overgrowth of several types of bacteria that naturally live in the vagina. While it can be associated with sex, it's not a sexually transmitted disease (STD) and can also occur independently of sex. Douching increases risk because it wipes out beneficial vaginal bacteria. BV is also more common in women who have used an intrauterine device, though it's not clear why.

Symptoms:

As many as 50 percent of affected women do not have any symptoms; those who do may notice a fishy vaginal odor; a thin gray or white discharge; itching in the vaginal area; and pain or a burning sensation while urinating. Although symptoms can be similar to those of a yeast infection, the condition is very different (it's caused by bacteria, not yeast) and cannot be treated with yeast medications.

Diagnosis:

A doctor examines the vagina and tests a sample of vaginal fluid for BV-causing bacteria.

Treatment:

While the condition may go away on its own, prompt treatment (generally with antibiotics) is essential, since the condition can increase the risk that a woman will develop pelvic inflammatory disease (which can lead to infertility), be susceptible to urinary-tract infections, or contract an STD if she's sexually active. For the estimated 16 percent of pregnant women affected, treating BV may reduce the risk of preterm delivery. Women are advised to abstain from sex during treatment and to use condoms for up to a month afterward. One in four women has a recurrence within 30 days of the first treatment, but 80 percent are treated effectively with an additional course of medication, according to Dr. Hillier.

Prevention:

To prevent BV, avoid douching, use condoms during sex, and have regular ob-gyn checkups. For more information, visit the Centers for Disease Control and Prevention at www.cdc.gov.

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