Improving Menstrual and VAginal Health for All (IMVAHA)

IMVAHA: Improving Menstrual and VAginal Health for All

A three-period crossover trial will study the effects of short-term use of 3 menstrual products (menstrual pad, tampon, menstrual cup) on the bacterial composition of the vaginal microbiome in three countries (Peru, Cameroon, and Switzerland). Each crossover period consists of two menstrual cycles, thus resulting in a 6-month trial. Participants will be randomly assigned to one of 6 exposure sequences (different order of products per sequence); in each sequence, participants will adopt each menstrual product for 2 menstrual cycles. Participants will provide vaginal microbiome samples via self-sample swabs at 3 points during each menstrual cycle. Given the crossover design of the study, there is not a dedicated control group.

Study Overview

• Status: Recruiting
• Conditions: Effects of Menstrual Products on the Vaginal Microbiome
• Intervention / Treatment: Other: Menstrual Pads; Other: Menstrual Cups; Other: Tampons

Detailed Description

In three countries, the investigators will follow a randomized crossover design to study the effects of menstrual products on the vaginal microbiome composition and diversity. Eligible participants who are willing to adopt pads, tampons and menstrual cups to manage their menstruation, and for which baseline composition of their vaginal microbiomes is determined through DNA sequencing of the 16s rRNA gene will enter a three-period crossover trial. Each period of the trial will consist of two menstrual cycles, thus resulting in a 6-month trial. Participants will be randomly assigned to one of six different exposure sequences of menstrual products, as follows:

i) Tampon, Cup, Pad ii) Tampon, Pad, Cup iii) Cup, Tampon, Pad iv) Cup, Pad, Tampon v) Pad, Tampon, Cup vi) Pad, Cup, Tampon

In group "i)", participants will adopt tampons during the first two menstrual cycles (first period of the trial), followed by the adoption of cups during the next two menstrual cycles (second period), and lastly menstrual pads for the next two menstrual cycles (third crossover period). In groups ii) to vi) following the same design but in different sequences. Self-sampling kits will be provided during six consecutive menstrual cycles, a few days before the start of menses. Each kit will contain swabs for three self-sampling points during the menstrual cycle and the corresponding menstrual products.

• Study Type: Interventional
• Enrollment (Estimated): 100
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Sonja Merten, MD MPH PhD; Phone Number: 0041-61-284-8387; Email: sonja.merten@swisstph.ch
• Study Contact Backup: Name: Monica Ticlla, PhD; Phone Number: 0041-61-284-8387; Email: monicaroxana.ticllaccenhua@swisstph.ch

Study Locations

• Cameroon
  • Yaoundé
    • Yaoundé, Yaoundé, Cameroon, 3
      • Recruiting
      • Centre de Recherche sur les Maladies Emergentes et Re-Emergentes
      • Contact: Esemu Livo, PhD; Phone Number: +237 674 632 078; Email: esemu_livo@yahoo.com
      • Contact: Marie Josiane Kenfack, PhD(c); Phone Number: +237676783165; Email: kenfackjosiane@yahoo.fr
• Peru
  • Iquitos
    • Iquitos, Iquitos, Peru, 16007
      • Recruiting
      • Universidad Nacional de la Amazonia Peruana
      • Contact: Viviana Pinedo, PhD; Phone Number: +51 955 850 853; Email: viviana.pinedo@unapiquitos.edu.pe
      • Contact: Sandra Condori, PhD; Phone Number: +32 488 15 54 52; Email: sandra.condori@uantwerpen.be
      • Sub-Investigator: Katty Arista, M.Sc
• Switzerland
  • Allschwil
    • Allschwil, Allschwil, Switzerland, 4123
      • Recruiting
      • Swiss Tropical and Public Health Institute
      • Contact: Sonja Merten, MD MPH PhD; Phone Number: +41 79 640 17 27; Email: sonja.merten@swisstph.ch
      • Contact: Monica Ticlla, PhD; Email: monicaroxana.ticllaccenhua@unibas.ch

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• able to provide informed consent;
• aged 18-35;
• residing in the recruitment region and expecting to reside in the same region for at least six months following recruitment (Yaoundé/ Gounougou, Cameroon; Loreto/Lima/Maynas provinces, Peru; or Basel-Landschaft and Basel-Stadt cantons, Switzerland);
• are native speakers or are able to read and understand one of the following languages in each respective country (German, French, Italian, English or Spanish in Switzerland; French or English in Cameroon; Spanish in Peru);
• had menstrual cycles of 21-35 days for at least the last 4 months;
• had menses which lasted at least 3 days for at least the last 4 months.

Exclusion criteria:

• experienced a menstrual abnormality with any of the menstrual cycles in the last 4 months (such as oligomenorrhea or amenorrhea, or bleed more than 7 days a month);
• are pregnant or actively trying to become pregnant;
• are breastfeeding;
• used antibiotics and/or vaginal antifungals in the last 30 days prior to recruitment;
• had a vaginal birth in the last 6 months;
• vaginal surgery, perineal surgery, uterine surgery, miscarriage or abortion in the last 6 months;
• history of Toxic Shock Syndrome ;
• positive to detection of the toxic shock syndrome toxin-1 gen (tst) using Polymerase Chain Reaction (PCR);
• Intrauterine device in situ;
• under medication (treatment against infectious or chronic disease) at the time of recruitment or during the 3 weeks prior to recruitment;
• clinical symptoms of vaginal infection;
• smoker.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: None (Open Label)

Number of Arms

6

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Other: TamponCupPad; Participants will adopt tampons during the first two menstrual cycles (first period of the trial), followed by adoption of cups during the next two menstrual cycles (second period), and lastly menstrual pads for the next two menstrual cycles (third crossover period).	Other: Menstrual Pads; Participants adopt menstrual pads to manage their menstruation during 2 menstrual cycles. For each menstrual cycle, participants will provide vaginal microbiome samples via self-sampled swabs at 3 points.; Other: Menstrual Cups; Participants adopt menstrual cups to manage their menstruation during 2 menstrual cycles. For each menstrual cycle, participants will provide vaginal microbiome samples via self-sampled swabs at 3 points.; Other: Tampons; Participants adopt tampons to manage their menstruation during 2 menstrual cycles. For each menstrual cycle, participants will provide vaginal microbiome samples via self-sampled swabs at 3 points.
Other: TamponPadCup; Participants will adopt tampons during the first two menstrual cycles (first period of the trial), followed by adoption of pads during the next two menstrual cycles (second period), and lastly menstrual cups for the next two menstrual cycles (third crossover period).	Other: Menstrual Pads; Participants adopt menstrual pads to manage their menstruation during 2 menstrual cycles. For each menstrual cycle, participants will provide vaginal microbiome samples via self-sampled swabs at 3 points.; Other: Menstrual Cups; Participants adopt menstrual cups to manage their menstruation during 2 menstrual cycles. For each menstrual cycle, participants will provide vaginal microbiome samples via self-sampled swabs at 3 points.; Other: Tampons; Participants adopt tampons to manage their menstruation during 2 menstrual cycles. For each menstrual cycle, participants will provide vaginal microbiome samples via self-sampled swabs at 3 points.
Other: CupTamponPad; Participants will adopt menstrual cups during the first two menstrual cycles (first period of the trial), followed by adoption of tampons during the next two menstrual cycles (second period), and lastly menstrual pads for the next two menstrual cycles (third crossover period).	Other: Menstrual Pads; Participants adopt menstrual pads to manage their menstruation during 2 menstrual cycles. For each menstrual cycle, participants will provide vaginal microbiome samples via self-sampled swabs at 3 points.; Other: Menstrual Cups; Participants adopt menstrual cups to manage their menstruation during 2 menstrual cycles. For each menstrual cycle, participants will provide vaginal microbiome samples via self-sampled swabs at 3 points.; Other: Tampons; Participants adopt tampons to manage their menstruation during 2 menstrual cycles. For each menstrual cycle, participants will provide vaginal microbiome samples via self-sampled swabs at 3 points.
Other: CupPadTampon; Participants will adopt menstrual cups during the first two menstrual cycles (first period of the trial), followed by adoption of menstrual pads during the next two menstrual cycles (second period), and lastly tampons for the next two menstrual cycles (third crossover period).	Other: Menstrual Pads; Participants adopt menstrual pads to manage their menstruation during 2 menstrual cycles. For each menstrual cycle, participants will provide vaginal microbiome samples via self-sampled swabs at 3 points.; Other: Menstrual Cups; Participants adopt menstrual cups to manage their menstruation during 2 menstrual cycles. For each menstrual cycle, participants will provide vaginal microbiome samples via self-sampled swabs at 3 points.; Other: Tampons; Participants adopt tampons to manage their menstruation during 2 menstrual cycles. For each menstrual cycle, participants will provide vaginal microbiome samples via self-sampled swabs at 3 points.
Other: PadTamponCup; Participants will adopt menstrual pads during the first two menstrual cycles (first period of the trial), followed by adoption of tampons during the next two menstrual cycles (second period), and lastly menstrual cups for the next two menstrual cycles (third crossover period).	Other: Menstrual Pads; Participants adopt menstrual pads to manage their menstruation during 2 menstrual cycles. For each menstrual cycle, participants will provide vaginal microbiome samples via self-sampled swabs at 3 points.; Other: Menstrual Cups; Participants adopt menstrual cups to manage their menstruation during 2 menstrual cycles. For each menstrual cycle, participants will provide vaginal microbiome samples via self-sampled swabs at 3 points.; Other: Tampons; Participants adopt tampons to manage their menstruation during 2 menstrual cycles. For each menstrual cycle, participants will provide vaginal microbiome samples via self-sampled swabs at 3 points.
Other: PadCupTampon; Participants will adopt menstrual pads during the first two menstrual cycles (first period of the trial), followed by adoption of menstrual cups during the next two menstrual cycles (second period), and lastly tampons for the next two menstrual cycles (third crossover period).	Other: Menstrual Pads; Participants adopt menstrual pads to manage their menstruation during 2 menstrual cycles. For each menstrual cycle, participants will provide vaginal microbiome samples via self-sampled swabs at 3 points.; Other: Menstrual Cups; Participants adopt menstrual cups to manage their menstruation during 2 menstrual cycles. For each menstrual cycle, participants will provide vaginal microbiome samples via self-sampled swabs at 3 points.; Other: Tampons; Participants adopt tampons to manage their menstruation during 2 menstrual cycles. For each menstrual cycle, participants will provide vaginal microbiome samples via self-sampled swabs at 3 points.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Log-ratio of Dialister to Lactobacillus crispatus relative abundances in vaginal swabs (continuous variable)	The abundances of each bacterial taxa are estimated from the DNA amplification and sequencing of amplicons from the 16S rRNA gene.	Monthly, after menstruation ends, through study completion, an average of 6 months.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Log-ratio of Bifidobacterium vaginalis to Lactobacillus relative abundances in vaginal swabs (continuous variable)	The abundances of each bacterial taxa are estimated from the DNA amplification and sequencing of amplicons from the 16S rRNA gene.	Monthly, after menstruation ends, through study completion, an average of 6 months.
Log-ratio of Prevotella to Lactobacillus relative abundances in vaginal swabs (continuous variable)	The abundances of each bacterial taxa are estimated from the DNA amplification and sequencing of amplicons from the 16S rRNA gene.	Monthly, after menstruation ends, through study completion, an average of 6 months.
Dominant taxon in vaginal swabs (categorical variable)	The dominant taxon in a vaginal swab is defined as the most abundant taxon found with a relative abundance of at least 30% of the total bacterial DNA sequences found in the sample.	Monthly, after menstruation ends, through study completion, an average of 6 months.
Community state type in vaginal swabs (categorical variable)	The community state type in a vaginal swab is defined using the VALENCIA algorithm as described in this article: France, M.T., Ma, B., Gajer, P. et al. VALENCIA: a nearest centroid classification method for vaginal microbial communities based on composition. Microbiome 8, 166 (2020). https://doi.org/10.1186/s40168-020-00934-6	Monthly, after menstruation ends, through study completion, an average of 6 months.
Total bacterial load in vaginal swabs (continuous variable)	Indirectly estimated with qPCR of the 16S rRNA gene	Monthly, after menstruation ends, through study completion, an average of 6 months.
Self-reported vaginal complaints (discrete variable)	Self-reported through follow up surveys along the six-month trial	Monthly, from enrollment until study completion, an average of 6 months.
Vaginal pH (ordinal variable)	Measured with a vaginal swab and a fixed indicator (3.6 - 6.1), just after menstruation ends.	Monthly, after menstruation ends, through study completion, an average of 6 months.
Alpha diversity (continuous variable)	Alpha diversity indices (e.g., Shannon, Simpson) are estimated for each vaginal swab sample to quantify microbial richness and evenness.	Monthly, after menstruation ends, through study completion, an average of 6 months.
Log-ratio of Gardnerella module to L. crispatus module relative abundances (continuous variable)	The abundances of each bacterial module are estimated from the DNA amplification and sequencing of amplicons from the 16S rRNA gene.	Monthly, after menstruation ends, through study completion, an average of 6 months.
Log-ratio of Prevotella module to L. crispatus module relative abundances (continuous variable)	The abundances of each bacterial module are estimated from the DNA amplification and sequencing of amplicons from the 16S rRNA gene.	Monthly, after menstruation ends, through study completion, an average of 6 months.
molBV score (discrete variable)	The molBV score in a vaginal swab is defined and derived as described in this article: Usyk, M., Schlecht, N.F., Pickering, S. et al. molBV reveals immune landscape of bacterial vaginosis and predicts human papillomavirus infection natural history. Nat Commun 13, 233 (2022). https://doi.org/10.1038/s41467-021-27628-3.	Monthly, after menstruation ends, through study completion, an average of 6 months.

Collaborators and Investigators

• Sponsor: Swiss Tropical & Public Health Institute
• Collaborators: Universidad Peruana Cayetano Heredia; Universiteit Antwerpen; Universidad Nacional de la Amazonia Peruana; Centre de Recherche sur les Maladies Emergentes et Re-Emergentes
• Investigators: Principal Investigator: Sonja Merten, PhD, Swiss Tropical & Public Health Institute

Publications and helpful links

General Publications

• Ticlla MR, Dumbaugh M, Condori-Catachura S, Kenfack J, Hattendorf J, Van Der Donck L, Arista KM, Arora N, Gebert S, Ackermann L, Ahannach S, Riveros M, Blas MM, Kenmoe S, Barriere FY, Shea AA, Pinedo-Cancino V, Rivas-Ruiz R, Di Cecco V, Esemu L, Ochoa TJ, Lebeer S, Martin Hilber A, Merten S. Improving menstrual and vaginal health for all (IMVAHA): protocol for a randomised cross-over trial assessing the impact of menstrual products on the vaginal microbiome of women aged 18-35 years in Cameroon, Peru and Switzerland. BMJ Open. 2026 Apr 22;16(4):e108568. doi: 10.1136/bmjopen-2025-108568.

Study record dates

Study Major Dates

• Study Start (Actual): April 15, 2026
• Primary Completion (Estimated): December 31, 2026
• Study Completion (Estimated): December 31, 2026

Study Registration Dates

• First Submitted: September 24, 2024
• First Submitted That Met QC Criteria: October 15, 2024
• First Posted (Actual): October 17, 2024

Study Record Updates

• Last Update Posted (Actual): April 23, 2026
• Last Update Submitted That Met QC Criteria: April 20, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: vaginal microbiome; menstruation; crossover study; menstrual products
• Additional Relevant MeSH Terms: Equipment and Supplies; Feminine Hygiene Products; Menstrual Hygiene Products
• Other Study ID Numbers: 2023-30

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No