Bacterial vaginosis is the most common vaginal condition in women of reproductive age, affecting roughly 1 in 4 women in the United States at any given time. National survey data put the overall prevalence at 27% among women aged 14 to 49, and global estimates are similar, ranging from 23% to 29% depending on the population studied. Despite how widespread it is, about half of all cases produce no noticeable symptoms, which means millions of women have BV without knowing it.
U.S. and Global Prevalence
The most comprehensive U.S. data comes from the National Health and Nutrition Examination Survey, which tested vaginal swabs from a nationally representative sample of women aged 14 to 49. That analysis found an overall BV prevalence of 27%. Globally, the World Health Organization cites a systematic review placing prevalence among reproductive-age women between 23% and 29%, making BV a near-universal health issue rather than one confined to any single region or healthcare system.
These numbers reflect a snapshot in time. Because BV can resolve on its own and then return, many more women will experience at least one episode over the course of their lives than the point-prevalence figures suggest.
Racial and Ethnic Disparities
BV rates are not evenly distributed across racial and ethnic groups. In one large pregnancy cohort, 22.3% of Black women had BV compared with 8.5% of white women, a gap of nearly threefold. Hispanic women fall somewhere in between in most studies. Researchers have linked these disparities to differences in vaginal microbiome composition, socioeconomic stressors, and access to care rather than to any inherent biological difference. The disparity is significant enough that public health agencies flag it as a contributor to downstream reproductive health inequities, including higher rates of preterm birth in Black communities.
How Common Is BV During Pregnancy?
Reported prevalence among pregnant women ranges from 10% to 35%, though some studies have documented rates as high as 50% depending on the population and the diagnostic method used. The concern during pregnancy is not just discomfort. A large meta-analysis found that pregnant women with BV face a 60% increased risk of preterm delivery. When BV is diagnosed in the first trimester specifically, the risks climb sharply: one study reported a nearly sevenfold increase in preterm delivery and a similar increase in premature rupture of membranes. Another study found that BV in the second trimester accounted for 83% of the attributable risk for preterm birth in that cohort.
These numbers help explain why some prenatal care protocols include BV screening, particularly for women with a history of preterm delivery.
Half of Cases Have No Symptoms
One of the reasons BV prevalence is so high is that roughly half of affected women are asymptomatic. They have the characteristic shift in vaginal bacteria, with a drop in protective lactobacilli and a rise in other organisms, but they never develop the telltale thin discharge or fishy odor that prompts a visit to a clinician. This matters because even asymptomatic BV can increase vulnerability to sexually transmitted infections. Women with BV have a 60% higher risk of acquiring HIV, and the condition has been linked to increased susceptibility to chlamydia, gonorrhea, and herpes as well.
Recurrence Makes the Numbers Worse
Standard antibiotic treatment clears BV in 80% to 90% of cases initially, but the condition is notoriously recurrent. Up to 60% of women who are successfully treated will have BV come back within 12 months. That recurrence rate is one of the most frustrating aspects of the condition, both for patients and for clinicians. Some newer treatment protocols that add a follow-up course of vaginal boric acid after antibiotics have brought the six-month recurrence rate down to around 30%, but even that means roughly one in three women will deal with BV again within half a year.
For women who experience repeated episodes, the pattern often feels cyclical: symptoms appear, antibiotics work, symptoms return weeks or months later. This cycle is common enough that recurrent BV is considered its own clinical category, generally defined as three or more confirmed episodes in a 12-month period.
What Drives the High Prevalence
BV is not a sexually transmitted infection in the traditional sense, but sexual activity is one of the strongest risk factors. Having a new sexual partner or multiple partners increases the likelihood of BV, likely because exposure to different genital microbiomes can disrupt the balance of vaginal bacteria. Douching is another well-established risk factor. It washes away the lactobacilli that keep vaginal pH low and protective, creating an environment where BV-associated bacteria thrive.
Other factors that contribute to prevalence include smoking, use of certain types of intrauterine devices, and lack of condom use. Women who have sex with women also experience high rates of BV, with some studies suggesting partner-to-partner transmission of the bacterial communities involved. Because so many common behaviors and exposures can tip the balance, the condition remains stubbornly prevalent across nearly every demographic group studied.