Vagina Menstrual cups help prevent infection, improve vaginal health (Jul 2023) 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

Michael Harrop

Active member
Jul 6, 2023

Teenage girls who were given menstrual cups were less likely to acquire certain kinds of vaginal infections and were more likely to have a healthy vaginal microbiome.



Nonhygienic products for managing menstruation are reported to cause reproductive tract infections. Menstrual cups are a potential solution. We assessed whether menstrual cups would reduce bacterial vaginosis (BV), vaginal microbiome (VMB), and sexually transmitted infections (STIs) as studies have not evaluated this.

Methods and findings​

A cluster randomized controlled trial was performed in 96 Kenyan secondary schools, randomized (1:1:1:1) to control, menstrual cup, cash transfer, or menstrual cup plus cash transfer. This substudy assessing the impact of menstrual cups on BV, VMB, and STIs, included 6 schools from the control (3) and menstrual cup only (3) groups, both receiving BV and STI testing and treatment at each visit. Self-collected vaginal swabs were used to measure VMB (16S rRNA gene amplicon sequencing), BV (Nugent score), and STIs. STIs were a composite of Chlamydia trachomatis and Neisseria gonorrhoeae (nucleic acid amplification test) and Trichomonas vaginalis (rapid immunochromatographic assay). Participants were not masked and were followed for 30 months. The primary outcome was diagnosis of BV; secondary outcomes were VMB and STIs. Intention-to-treat blinded analyses used mixed effects generalized linear regressions, with random effects term for school. The study was conducted between May 2, 2018, and February 7, 2021. A total of 436 participants were included: 213 cup, 223 control. There were 289 BV diagnoses: 162 among control participants and 127 among intervention participants (odds ratio 0.76 [95% CI 0.59 to 0.98]; p = 0.038). The occurrence of Lactobacillus crispatus–dominated VMB was higher among cup group participants (odds ratio 1.37 [95% CI 1.06 to 1.75]), as was the mean relative abundance of L. crispatus (3.95% [95% CI 1.92 to 5.99]). There was no effect of intervention on STIs (relative risk 0.82 [95% CI 0.50 to 1.35]). The primary limitations of this study were insufficient power for subgroup analyses, and generalizability of findings to nonschool and other global settings.


Menstrual cups with BV and STI testing and treatment benefitted adolescent schoolgirls through lower occurrence of BV and higher L. crispatus compared with only BV and STI testing and treatment during the 30 months of a cluster randomized menstrual cup intervention.

Author summary​

Why was this study done?​

  • Many girls in low- and middle-income countries are unable to adequately manage their menses and can suffer reproductive tract infections resulting from use of inappropriate materials.
  • Reusable menstrual cups are medical grade silicone bell-shaped chambers that are inserted into the vagina to capture menstrual blood. Menstrual cups are safe and have not been associated with changes in vaginal pH or microflora.
  • It is not known whether menstrual cups could lead to improvements in reproductive tract health.

What did the researchers do and find?​

  • We assessed the impact of menstrual cups on the vaginal microbiome (VMB), bacterial vaginosis (BV), and sexually transmitted infections (STIs) in 436 secondary schoolgirls in western Kenya.
  • During the 30-month cluster randomized controlled trial, BV and VMB composition were assessed every 6 months, and STIs (gonorrhea, chlamydia, and trichomoniasis) were assessed annually, with testing and treatment for BV and STIs for intervention and control participants regardless of symptoms.
  • Among the intervention group, in crude analyses, the occurrence of BV was 24% lower than control participants, while the proportion of Lactobacillus crispatus–dominated community state type was 37% higher.

What do these findings mean?​

  • Other studies have found that menstrual cups are a safe and cost-effective tool for menstrual hygiene management.
  • These results provide evidence they can promote an optimal VMB and reduce BV for adolescent girls.
  • Further research should investigate the constitution of the VMB and incidence of BV and STIs in different age groups and populations using menstrual cups.

Collection of info on prevention and treatment of BV (bacterial vaginosis), and the vaginal microbiome.
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