Many women will experience bacterial vaginosis (BV) at some point in their lives, yet it remains one of the least talked-about vaginal health issues. BV can be uncomfortable, frustrating, and persistent. And when it shows up during pregnancy, it often brings an extra layer of worry.
This article aims to help you understand what bacterial vaginosis is, how it affects pregnancy health, when treatment is necessary, and gentle ways to support your microbiome alongside your provider’s recommendations.
What Is Bacterial Vaginosis?
Bacterial vaginosis is an imbalance of the vaginal microbiome. The prevalence of bacterial vaginosis among females fluctuates from 20% to 60% across various countries, in the United States, bacterial vaginosis rates are approximately 30% (1). In a healthy state, the vagina is dominated by Lactobacillus species-friendly bacteria that produce lactic acid and keep the pH slightly acidic. This acidity is protective: it keeps pathogens in check and maintains healthy vaginal tissue.
In bacterial vaginosis, the protective lactobacilli decreases and other bacteria – especially Gardnerella vaginalis and other anaerobes – begin to overgrow. This imbalance shifts the pH upward, leading to the hallmark BV symptoms: a thin gray or white discharge, a noticeable “fishy” odor (often stronger after sex), and mild irritation or itching (1). Some women experience no symptoms at all, and BV is discovered through routine testing (1).
BV is not a sexually transmitted infection, though sex can influence the vaginal environment in ways that make BV more likely to develop or return.
Approximately 30% of bacterial vaginosis cases resolve on their own without treatment, and treatment is not indicated for asymptomatic Gardnerella colonization. There is currently insufficient evidence that treating asymptomatic BV improves pregnancy or health outcomes.
Why Does BV Happen?
The vaginal microbiome is sensitive. Small changes in pH, hormones, or local immunity can shift the balance.
Common contributors include:
- Changes in sexual activity
- Alterations in vaginal pH from semen
- Hormonal fluctuations (especially around pregnancy and postpartum)
- Antibiotic use
- Stress and immune shifts
- Vaginal irritants such as scented soaps, washes, or douching
- Changes in the gut microbiome that affect the vaginal microbiome through the gut-vagina axis
Some women find that they are more prone to bacterial vaginosis during pregnancy. This is likely because the hormonal and immune changes of pregnancy can make the vaginal environment less stable and more vulnerable to imbalance.
How Is Bacterial Vaginosis Diagnosed?
A healthcare provider can diagnose BV through vaginal swab testing, either with a rapid in-office test or a laboratory NAAT/culture panel (1). Diagnosis is important because bacterial vaginosis shares symptoms with yeast infections, trichomoniasis, and other causes of vaginal irritation, and treatments differ.
Bacterial Vaginosis in Pregnancy
During pregnancy, the vaginal microbiome naturally undergoes changes, but a balanced Lactobacillus-dominant ecosystem remains important. Research shows that untreated symptomatic bacterial vaginosis in pregnancy may increase the risk of certain complications, including:
- Preterm labor
- Preterm premature rupture of membranes (PPROM)
- Low birth weight
- Postpartum uterine infections
It’s important to note that these risks are largely associated with symptomatic BV and with more severe shifts in the microbiome (1). Many women with mild or asymptomatic bacterial vaginosis go on to have healthy, full-term pregnancies. In the case of symptomatic bacterial vaginosis, some studies suggest that treating symptomatic bacterial vaginosis before 22 weeks may reduce the risk of preterm labor, though evidence is mixed and at this time no consensus exists for universal screening (1).
How Bacterial Vaginosis Is Treated
The standard medical treatments for bacterial vaginosis are either oral or topical metronidazole or clindamycin, which are both considered safe during pregnancy. Both metronidazole and clindamycin are considered effective when taken orally or used vaginally, with cure rates around 80–90% within one month, but recurrence is common with up to 80% of women experiencing recurrent BV within 9 months. This happens because antibiotics clear the overgrowth but do not rebuild the beneficial lactobacilli that stabilize the vaginal microbiome long-term.
The 10-15% of women who do not improve after the first course of antibiotics may require another round of treatment and likely benefit from integrative microbiome support.
Supporting the Vaginal Microbiome Naturally
While antibiotics can treat bacterial overgrowth, they do not rebuild a balanced vaginal flora. The vaginal microbiome thrives with the same steady whole-body support that benefits the gut, hormones, and immune system.
Avoiding vaginal irritants like scented washes, harsh soaps, and especially douching helps protect the mucosal barrier and prevents pH shifts that wash away protective Lactobacillus species. Even small increases in pH make it harder for beneficial bacteria to dominate and maintain the naturally acidic environment that discourages BV-associated organisms.
Gut health also directly shapes vaginal health (2). Many vaginal Lactobacillus strains originate in the gastrointestinal tract, meaning a diverse, fiber-rich, fermented-food-supported gut increases the likelihood of healthy vaginal recolonization after treatment. Probiotics may offer additional support in restoring Lactobacillus dominance.
Some evidence suggests that Lactobacillus reuteri and Lactobacillus rhamnosus may be particularly beneficial in supporting a healthy vaginal microbiome (3). When the gut is balanced, the recurrence of BV tends to be lower.
To learn more, read these articles:
- What Is Leaky Gut, And How Do You Heal It?
- Restoring Gut Health After Antibiotics: A Guide For Families
Some women notice symptoms after intercourse because semen’s higher pH temporarily reduces vaginal acidity. Emptying the bladder afterward, rinsing externally with water only, and using condoms when appropriate can help minimize these fluctuations.
Stress reduction is another powerful tool. Elevated cortisol alters immune function and can shift the vaginal microbiome away from Lactobacillus dominance. Consistent sleep, gentle movement, and nervous-system support make it easier for the microbiome to stabilize.
These small, steady habits help guide the vaginal ecosystem back to a low-pH, Lactobacillus-dominant state.
Bacterial Vaginosis FAQs
1. Is BV Dangerous for My Baby?
This is one of the most common questions pregnant women ask. The truth is reassuring: bacterial vaginosis itself does not pass to your baby and does not directly cause fetal infection. The concern is more about the inflammatory environment bacterial vaginosis can create in the uterus or membranes if left untreated. Treating symptomatic bacterial vaginosis significantly reduces the risk, and most women go on to have completely healthy outcomes.
2. Can BV Cause Miscarriage?
Some studies suggest that severe or untreated BV, particularly in early pregnancy, may be associated with an increased risk of miscarriage. However, the data is mixed and does not show a clear causal relationship. What we do know is that treating symptomatic BV early and supporting the microbiome creates a healthier environment for pregnancy.
3. What About Treating Partners?
Because bacterial vaginosis is not an STI, partners do not need treatment (1). Evidence shows that treating partners does not reduce symptoms, improve clinical outcomes, or prevent recurrence.
4. What’s the Difference Between BV and Yeast Infections?
It’s common for pregnant women to misinterpret discharge changes because both BV and yeast infections can show up more frequently during this time. BV typically causes a thin, grayish discharge with odor, while yeast infections cause thick, white, clumpy discharge with itching and no odor.
Because treatments differ, proper testing is important instead of guessing based on symptoms alone.
When to Seek Medical Care for Bacterial Vaginosis
It is important to be evaluated by your healthcare provider if you notice symptoms of bacterial vaginosis during pregnancy, especially if this is your first time experiencing discharge changes. You should also seek evaluation if:
- You have pelvic cramping, pressure, or pain
- You notice bleeding
- Symptoms persist after treatment
- There are recurrent infections within months
Trust your intuition – if something feels off, it is always appropriate to reach out to your provider.
Summary
Bacterial vaginosis is extremely common (about 30% of women in the U.S. have it), and many cases cause no symptoms and can resolve on their own. BV happens when protective Lactobacillus bacteria decrease and other bacteria overgrow, leading to discharge and odor.
Bacterial vaginosis is not an STI, and treating partners doesn’t help prevent recurrence.
During pregnancy, symptomatic BV (not mild or asymptomatic BV) is linked with higher risk of complications like preterm labor and preterm premature rupture of membranes. Treating symptomatic bacterial vaginosis is recommended and safe, with cure rates of 80-90%, though recurrence is common because antibiotics clear the overgrowth but don’t rebuild the microbiome, which is why microbiome support matters.
Most women with bacterial vaginosis in pregnancy – especially when treated – go on to have completely healthy pregnancies and births.
References:
- Kairys N, Carlson K, Garg M. Bacterial Vaginosis. [Updated 2024 May 6]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK459216/
- Amabebe E, Anumba DOC. Female Gut and Genital Tract Microbiota-Induced Crosstalk and Differential Effects of Short-Chain Fatty Acids on Immune Sequelae. Front Immunol. 2020 Sep 10;11:2184. doi: 10.3389/fimmu.2020.02184. PMID: 33013918; PMCID: PMC7511578.
- Anukam, K., Osazuwa, E., Ahonkhai, I., Ngwu, M., Osemene, G., Bruce, A. W., & Reid, G. (2006). Augmentation of antimicrobial metronidazole therapy of bacterial vaginosis with oral probiotic Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14: randomized, double-blind, placebo controlled trial. Microbes and Infection, 8(6), 1450–1454. https://doi.org/10.1016/j.micinf.2006.01.003
