Bacterial vaginosis is not dangerous in most cases, but leaving it untreated raises your risk for several serious complications, especially during pregnancy. BV is the most common vaginal condition in women ages 15 to 44, and while many people experience only mild symptoms or none at all, the infection can create conditions in the body that lead to bigger problems over time.
What BV Does to Your Body
BV happens when the balance of bacteria in the vagina shifts. Normally, beneficial bacteria keep the vaginal environment slightly acidic, which discourages harmful organisms from growing. When BV develops, that protective acidity drops and less helpful bacteria take over. This disrupted environment is what drives the complications associated with BV, not the condition itself being immediately harmful.
Most people with BV notice a thin, grayish-white discharge with a fishy odor, particularly after sex. But roughly half of all women with BV have no symptoms at all, which means the condition can persist quietly for weeks or months without treatment.
Pregnancy Risks Are the Biggest Concern
The most well-documented dangers of BV involve pregnancy. In one study published in Frontiers in Surgery, women with BV had a preterm birth rate (before 34 weeks) of 22.7%, compared to just 6.2% in women without BV. Babies born to mothers with BV also had significantly lower median birth weight: 2,450 grams versus 2,950 grams.
Those numbers represent real clinical differences. A baby born before 34 weeks often needs intensive care and faces a higher risk of long-term developmental issues. The lower birth weight associated with BV can also contribute to feeding difficulties and slower early growth. If you’re pregnant or planning to become pregnant and notice symptoms of BV, getting tested is important. Treatment during pregnancy is straightforward and can reduce these risks.
Increased Vulnerability to STIs
The disrupted vaginal environment created by BV makes it easier for sexually transmitted infections to take hold. When protective bacteria are depleted and vaginal pH rises, the tissue lining the vagina becomes more susceptible to infection. This includes HIV, chlamydia, gonorrhea, and herpes. BV doesn’t cause these infections, but it lowers your body’s natural defenses against them.
This is one of the less obvious dangers of BV. If you’re sexually active and have untreated BV, your baseline risk of picking up an STI from an infected partner is higher than it would be otherwise.
The Link to Pelvic Inflammatory Disease
BV is frequently present in women who develop pelvic inflammatory disease, a serious infection of the uterus, fallopian tubes, or ovaries. PID can cause chronic pelvic pain, scarring of the reproductive organs, and fertility problems. According to CDC treatment guidelines, BV is often found alongside PID, and treatment regimens for PID typically include antibiotics that also clear BV.
The relationship between the two conditions isn’t perfectly straightforward. Having BV doesn’t guarantee you’ll develop PID, and researchers haven’t confirmed that treating BV alone prevents PID. But the association is strong enough that clinicians take it seriously, particularly in women with recurring BV or additional risk factors like untreated STIs.
Postsurgical Infection Risk
Women who have untreated BV before gynecological procedures, including hysterectomy and abortion, face a higher risk of postsurgical infections. The overgrowth of harmful bacteria in the vagina can migrate into the surgical site, leading to complications that would otherwise be uncommon. This is why screening for BV before scheduled gynecological surgery is standard practice in many clinics.
Recurrence Is Extremely Common
One of the most frustrating aspects of BV is how often it comes back. Between 50% and 80% of women experience a recurrence within 6 to 12 months of finishing antibiotic treatment. The American College of Obstetricians and Gynecologists puts the figure at up to 66% within a year. That high recurrence rate means many women cycle through repeated rounds of antibiotics without lasting resolution, and each episode carries the same associated risks.
A growing body of evidence points to sexual activity as a significant factor in recurrence. In a notable shift, ACOG now recommends considering concurrent treatment of male sexual partners for women with recurrent BV. The recommendation includes a combination of oral and topical antibiotics for male partners. Previously, partner treatment wasn’t considered beneficial based on available data, but newer research has changed that thinking. For same-sex partners and first-time BV cases, the decision to treat partners is made on a case-by-case basis through shared decision-making.
When BV Is and Isn’t a Concern
A single episode of BV that responds to treatment and doesn’t recur is unlikely to cause lasting harm. The real danger lies in BV that goes undiagnosed, persists untreated, or keeps coming back. Chronic or recurring BV increases cumulative exposure to all of the risks above: higher STI susceptibility, greater chance of PID, and ongoing disruption of vaginal health.
If you have no symptoms and aren’t pregnant, BV may not need treatment at all, since it sometimes resolves on its own. But if you’re experiencing symptoms, are pregnant, are about to have a gynecological procedure, or keep getting reinfected, treatment matters. The condition itself won’t put you in the hospital, but the complications it enables can have lasting consequences for your reproductive health.