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Menstrual Cups Reduce Bacterial Vaginosis Risk and Improve Vaginal Health

A menstrual cup.
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Researchers from the University of Illinois Chicago (UIC) conducted a study exploring the effects of menstrual cup use on vaginal infection, sexually transmitted infection (STI) occurrence and the vaginal microbiome. The study is published in PLOS Medicine.

Menstrual hygiene management discrepancies

In many countries, people who menstruate can access a variety of menstrual products, but in low- and middle-income countries where “period poverty” is highly prevalent, the landscape of menstrual hygiene management (MHM) looks very different.

Reusable menstrual cups that are made from medical-grade silicone are a cost-effective approach to combatting period poverty. Bell-shaped, they can be inserted into the vagina to capture menstrual blood, before being removed, washed and used again.

In 2016, Professor Penelope Phillips-Howard from the Liverpool School of Tropical Medicine conducted a randomized trial exploring the effects of menstrual hygiene on schoolgirls’ school and health outcomes in Kenya. She discussed preliminary findings suggesting that menstrual cups are effective at reducing vaginal infections with Dr. Supriya Mehta, an adjunct professor of epidemiology and biostatistics in the School of Public Health at UIC. Mehta believed this positive outcome seen with menstrual cup use was because the products support a healthy microbiome during menstruation: “If your vagina is healthy, then it’s more resilient to STI pathogens,” she says. But to confirm her hypothesis, more data was needed.

Menstrual cups reduce bacterial vaginosis occurrence

With funding from the National Institutes of Health (NIH), Mehta and colleagues embarked on a sub-study, recruiting 436 Kenyan secondary school girls that were part of Phillips-Howard’s larger study. Half of the girls were randomly assigned to receive a menstrual cup. Through vaginal swabbing, all participants were tested for bacterial vaginosis (BV) every 6 months, and STIs (including gonorrhea, chlamydia and trichomoniasis) at 12 and 30 months. The vaginal swabs were also used to analyze the participants’ vaginal microbiome.

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Across the cohort of participants, there were 289 BV diagnoses – 162 among control participants and 127 among intervention participants. This equates to a 24% reduction in BV occurrence among menstrual cup users compared to the control group. While the researchers did not find menstrual cups to reduce STI risk significantly, when they controlled for confounding factors – such as sexual activity and the participants age – they saw a decrease in the number of STIs among participants using the product. “The results showed that menstrual cups could be a game-changer in helping keep girls healthy,” says Mehta.

Mehta and colleagues found the proportion of Lactobacillus crispatus bacterium in the vaginal microbiome to be 37% higher in cup users. This bacterium is associated with vaginal health, and is reduced when dysbiosis – an imbalance in the microbiome associated with disease – occurs. The researchers propose that menstrual cups are more beneficial for the vaginal microbiome compared to other products because they remove blood from the vaginal vault. Tampons, in contrast, don’t – which means the vaginal vault becomes an environment rich in iron, an inviting home for bacteria that can cause infections.

For Mehta, the results of this study are widely applicable to all menstruating individuals, and she encourages researchers in the field to replicate the work in other countries. The team behind this study received a further $2.6 million from the NIH to continue the study for one year, and Mehta plans to launch an additional project that focuses on sex workers in Kenya.

Reference: Mehta SD, Zulaika G, Agingu W, et al. Analysis of bacterial vaginosis, the vaginal microbiome, and sexually transmitted infections following the provision of menstrual cups in Kenyan schools: Results of a nested study within a cluster randomized controlled trial. PLOS Med. 2023;20(7):e1004258. doi:10.1371/journal.pmed.1004258

This article is a rework of a press release issued by the University of Illinois Chicago. Material has been edited for length and content.