Menstrual cup: reassuring findings regarding infection risk

A menstrual cup is an intravaginal device that comes in different sizes, depending on the model. Unlike an IUD, it is not inserted into the uterus. Instead, it sits in the vagina and collects menstrual blood. As a reusable menstrual product, the menstrual cup has progressively become more popular alongside conventional products such as tampons, as well as newer alternatives such as period underwear. However, despite the growing use of menstrual cups for menstrual hygiene, their potential effects on the vaginal microbiota, infections, and reproductive health have not yet been extensively studied.
This underlines the importance of this systematic review and meta-analysis¹ that investigated the relationship between menstrual cup use for menstrual protection and reproductive tract infections (RTIs), sexually transmitted infections (STIs), and the vaginal microbiota.

No increased risk of infection 

A total of 11 studies were included in the review, 8 of which were published after 2019. Together, they involved 10,268 adult and adolescent women from Africa (Kenya and Tanzania), the Americas (Brazil and the United States), and Europe (France, Belgium, and Denmark). One important limitation is that only three of the studies were considered to be of high quality. This limits both the overall scope of the review and the robustness of the results.Despite this limitation, the findings are broadly reassuring—and even encouraging—with regard to the use of menstrual cups: no increased risk of infection was observed among menstrual cup users for the infections evaluated. 
The findings actually point in the opposite direction. Observational studies and randomized trials conducted across three continents found a lower prevalence of bacterial vaginosis among menstrual cup users (around -20%).
Menstrual cup use also appears to be associated with a lower prevalence of STIs (- 26 %) than other menstrual products and protection methods. This finding comes from two randomized controlled trials conducted among young women in Kenya. One trial also suggested a possible reduction in the risk of HSV-2 (herpes simplex virus type 2) infection, although the difference did not quite reach statistical significance.

A beneficial effect on the vaginal flora?

Regarding the vaginal microbiota, menstrual cup users appear more likely to have a community-state type I (CST-I) microbiota, characterized by a predominance of Lactobacillus crispatus. This was observed in populations from the three European countries and in Kenya. This potential benefit may be partly explained by how the cup works. By collecting menstrual blood in the upper part of the vagina, the cup may reduce the exposure of the vaginal microbiota to iron-rich blood, which can promote the growth of Gardnerella vaginalis and L. iners. Menstrual cups may therefore help preserve a healthy vaginal microbiota dominated by L. crispatus, a profile associated with greater protection against vaginal dysbiosis and certain STIs. No cases of toxic shock syndrome were reported among menstrual cup users in the two studies that provided this information.
Overall, the authors conclude that menstrual cups represent an affordable, easy-to-implement, and sustainable option that could help reduce the burden of preventable gynecological conditions while supporting menstrual and intimate hygiene.