Untreated bacterial vaginosis (BV) raises your risk for several complications, including pelvic inflammatory disease, sexually transmitted infections, pregnancy problems, and post-surgical infections. Many cases of BV are mild or even symptom-free, and some resolve on their own, but leaving it unchecked gives harmful bacteria time to damage the vaginal environment in ways that can cascade into bigger health problems.
How BV Changes Your Vaginal Environment
A healthy vagina is dominated by beneficial bacteria that produce lactic acid, keeping the pH below 4.5. That acidic environment acts as a natural defense system. Lactic acid actively inhibits the growth of pathogens like chlamydia, gonorrhea, and even HIV.
When BV develops, harmful bacteria displace those protective species and form a sticky biofilm on the vaginal lining. These bacteria produce compounds that raise vaginal pH (causing the characteristic fishy odor) and break down the protective mucous layer of the vaginal wall. Once that barrier is compromised, secondary bacteria can attach more easily, and the imbalance deepens over time. This is why BV doesn’t just sit still. Left alone, the environment becomes progressively more hospitable to infections you’d otherwise be better equipped to fight off.
Increased Risk of STIs and HIV
Because BV strips away the vagina’s natural chemical and physical defenses, it makes you significantly more vulnerable to sexually transmitted infections. A meta-analysis published in several studies found that BV increases the risk of acquiring HIV by roughly 60%. That figure held up across multiple study designs and populations. People who already have HIV and develop BV are also more likely to transmit the virus to a partner.
The same disrupted environment increases susceptibility to chlamydia and gonorrhea. Those infections on their own can damage reproductive organs, so the combination of BV and an STI can compound the harm considerably.
Pelvic Inflammatory Disease and Fertility
BV can trigger pelvic inflammatory disease (PID), an infection of the uterus, fallopian tubes, or ovaries. PID often develops when bacteria from the vagina travel upward into the reproductive tract, something that’s far more likely when the vaginal microbiome is out of balance. Untreated PID can scar the fallopian tubes and lead to difficulty getting pregnant.
Research bears out this connection. A systematic review in the journal Human Reproduction found that BV is nearly three times as prevalent in women with tubal factor infertility compared to women with other causes of infertility. While the study designs don’t prove BV directly caused the tubal damage in every case, researchers describe the circumstantial evidence linking BV to tubal infertility as strong. The most likely pathway runs through PID: BV enables it, PID scars the tubes, and scarred tubes block or impair fertility.
Complications During Pregnancy
BV during pregnancy is linked to a higher rate of preterm delivery. In one study that followed pregnant women without treating their BV, the preterm delivery rate was significantly higher in the BV group compared to women with a normal vaginal microbiome. The condition is also associated with premature rupture of membranes, the breaking of the water sac before labor is due.
Despite these risks, routine screening and treatment of BV in all pregnant women hasn’t been shown to reduce preterm birth in large trials. Current CDC guidelines don’t recommend blanket screening for asymptomatic pregnant women. Treatment is recommended when symptoms are present, and your provider may weigh individual risk factors when deciding whether to test or treat.
Higher Infection Risk After Surgery
If you have BV at the time of a gynecological procedure, your odds of developing a post-operative infection climb substantially. Women with BV face roughly three to four times the risk of infections like vaginal cuff cellulitis or pelvic abscess after a hysterectomy, compared to women without BV. In one study, 35% of women with BV developed post-hysterectomy infections versus just 8% of women without it.
The risk extends to other procedures as well. After surgical abortions, women with untreated BV developed upper genital tract infections at about twice the rate of those who received antibiotics beforehand (16% vs. 8.5%). This is one reason many clinicians screen for BV before planned gynecological surgeries.
The Recurrence Problem
One of the most frustrating aspects of BV is how often it comes back after treatment. Standard antibiotic therapy kills the harmful bacteria but doesn’t directly restore the healthy ones. In one study, women’s vaginal microbiomes showed a rebound in beneficial lactobacilli one week after antibiotic treatment, but those gains disappeared within a month. Women with a history of recurrent BV consistently have lower levels of protective bacteria than women who’ve never had it.
This matters because each episode of BV resets the cycle of risk. Every round of dysbiosis is another window of vulnerability to STIs, another opportunity for bacteria to ascend into the reproductive tract, and another stretch of time where the vaginal lining’s defenses are weakened. Chronic, recurring BV isn’t just an annoyance. It represents a prolonged state of immune compromise in the reproductive tract.
What About Asymptomatic BV
Most women with BV don’t have noticeable symptoms. In a nationally representative survey, the majority of BV cases were asymptomatic. This raises a natural question: if you can’t feel it, does it still matter?
The answer is nuanced. In a six-month study of mostly asymptomatic women, 36% still had signs of BV at the end of the observation period, meaning more than a third of cases persisted without clearing on their own. Only about 19% of asymptomatic women in a placebo-controlled trial went on to develop symptoms within a month. So while many asymptomatic cases linger quietly, not all of them progress to something you’d notice.
The underlying risks, however, don’t require symptoms to be active. The elevated susceptibility to STIs and the potential for bacteria to reach the upper reproductive tract exist whether or not you experience discharge or odor. Current guidelines recommend treatment only for symptomatic BV, but being aware of the condition’s silent risks can help you make informed decisions about testing, especially before pregnancy or surgery.