Vaginal Microbiome Research
What research shows about the bacteria of the vagina, community types, bacterial vaginosis, pregnancy and HPV links, and the experimental status of live-bacteria treatments.
Content last updated . This page has not been medically reviewed.
Why this microbiome is different
Researchers sort vaginal samples into "community state types" (CSTs): types dominated by particular Lactobacillus species, or a "low-lactobacilli" type. [1] In the pregnancy studies below, it is the low-lactobacilli type that goes with higher risk. See Why There Is No Single Universal "Healthy Microbiome" for why this varies by body site.Evidence labels: approved medicine, established, promising but limited, mixed, insufficient evidence, preclinical (cells/animals only).
Bacterial vaginosis (BV)
The NHS describes BV as a common cause of unusual discharge caused by an imbalance of bacteria in the vagina. It is not classed as a sexually transmitted infection, though sex can trigger it, and half of women with BV have no symptoms. [2] It is usually treated with prescribed antibiotic tablets, gels or creams. [2] It often comes back within a few months. [2]Label: established as a recognized condition with standard antibiotic treatment. See the clinical safety side at Women's Health: When to Get Help.
The NHS advice on prevention is plain: use water and plain soap on the genital area, and do not use vaginal deodorants, washes or douches. [2] Marketing for "vaginal microbiome balancing" products that cleanse or wash is not supported by this.
HPV and cervical changes
A network meta-analysis found that communities dominated by non-Lactobacillus species or Lactobacillus iners were associated with three to five times higher odds of any human papillomavirus (HPV) infection compared with L. crispatus-dominant communities. [4] Again this is association only: it does not show that a community causes HPV, and it does not replace cervical screening.Who should talk to a clinician
Anyone with new or changed discharge, odor, pain, or bleeding, anyone who is pregnant, and anyone who keeps getting BV should see a clinician before trying any product. [2]How to evaluate claims
- Does the study measure a symptom, a recurrence, or only the bacteria that were counted?
- Was it a randomized trial against placebo, or an observational comparison?
- Is a product described as "restoring" the microbiome with no recurrence data?
Frequently asked questions
Is a vaginal microbiome test useful?
A community type is a research category. The studies above link types with outcomes in groups, not with a diagnosis in one person. See Microbiome Tests. [1]
Does bacterial vaginosis always cause problems in pregnancy?
No. The NHS says there is a small chance of complications such as premature birth or miscarriage, and that BV causes no problems in the majority of pregnancies. [2]
Can I prevent BV with probiotics?
The randomized evidence I read is one phase 2b trial of one strain used after antibiotics, and I could not verify that it is an approved product. [5]
Are douches or washes recommended?
No. The NHS advises against vaginal deodorants, washes and douches. [2]
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Community types and pregnancy
Label: promising but limited; these are associations, and a community type is not a diagnosis. The NHS advises people who are pregnant and notice changed discharge to speak to a GP or midwife. [2]
Treatments that add bacteria: approved versus experimental
- Antibiotics are the standard BV treatment. [2]
- Lactin-V (a Lactobacillus crispatus strain). In a randomized, double-blind, placebo-controlled phase 2b trial of 228 women who had first completed metronidazole gel, BV returned by week 12 in 30% given Lactin-V and 45% given placebo (risk ratio 0.66, 95% CI 0.44 to 0.87). Reported adverse events were similar in both groups. [5] Label: promising but limited / investigational. I did not verify a regulatory approval for this product in any country, so none is claimed here. Related background: Live Biotherapeutic Products.
- Vaginal microbiota transplantation. A scoping review through October 2023 found published human data from only 36 women across three studies, with promising results but small numbers, plus five registered trials ongoing. [6] Label: investigational; insufficient evidence. This is a clinical research procedure. Do not try it at home or with material from another person.
- Probiotic products are a separate topic: a result for one strain does not carry over to others. See Probiotic Strains and Labels.
References
- Citation: Gudnadottir et al. The vaginal microbiome and the risk of preterm birth: systematic review and network meta-analysis (Sci Rep 2022). Read 2026-10-22.
- Citation: NHS. Bacterial vaginosis (page last reviewed 19 June 2026). Read 2026-10-22.
- Citation: Ferrante et al. The vaginal microbiota and preterm birth: A systematic review (Eur J Obstet Gynecol Reprod Biol 2025). Read 2026-10-22.
- Citation: Norenhag et al. The vaginal microbiota, human papillomavirus and cervical dysplasia: systematic review and network meta-analysis (BJOG 2020). Read 2026-10-22.
- Citation: Cohen et al. Randomized Trial of Lactin-V to Prevent Recurrence of Bacterial Vaginosis (N Engl J Med 2020). Read 2026-10-22.
- Citation: Luo et al. The effectiveness of vaginal microbiota transplantation for vaginal dysbiosis and bacterial vaginosis: a scoping review (Arch Gynecol Obstet 2024). Read 2026-10-22.