Scientists Just Found Microplastics in Menstrual Blood
If you've seen headlines this year about plastic turning up in menstrual blood, you're not imagining it — it's real, it's new, and it's worth understanding properly rather than panicking about. So let's break down what the study actually found, what it doesn't (yet) prove, and what it means for the choices you make each cycle.
What the study found
Published in NanoImpact in early 2026, the study (led by Sharma and colleagues) did something researchers hadn't done before: it looked for microplastics inside menstrual blood and matched it against amniotic fluid from the same participants.
Using a plastic-free collection process and three separate detection methods layered together for accuracy, the researchers found:
- Microplastics in 100% of samples — every single menstrual blood and amniotic fluid sample tested contained plastic particles
- 136 particles characterised across all the samples analysed
- Six different polymer types identified, including polyethylene terephthalate (PET — common in polyester fabric and bottled water) and polycarbonate and polystyrene, which showed up most often
- Higher concentrations in menstrual blood than in amniotic fluid, in the same women
That last point is the one worth sitting with. Menstrual blood isn't just blood — it's a mix of blood, endometrial tissue and cervicovaginal fluid, shed from inside the reproductive tract. Finding higher plastic concentrations there hints that reproductive tissue itself might be a site where microplastics build up, not just a place they briefly pass through.
What it doesn't mean yet
This is where we want to be straight with you, because "microplastics in reproductive tissue" is the kind of headline that's easy to run away with.
The study is small (12 participants, one lab) and it's a biomonitoring study, not an outcomes study. That means it confirms plastic is present — it doesn't tell us:
- Whether this is linked to infertility, endometriosis or pregnancy complications
- Whether period products specifically are the source (the researchers didn't track which products participants used)
- Whether higher levels predict any particular health outcome
In other words: this is the first solid measurement of something researchers hadn't thought to look for. It's the start of a research thread, not the end of one. The scientists themselves are calling for replication across more labs and larger groups before drawing firm conclusions.
Why we're paying attention anyway
You don't need a definitive causal study to make sensible decisions about what sits against your body for hours at a time, especially against mucous membranes, which absorb far more readily than skin.
The researchers pointed to a few plausible pathways plastic could reach reproductive tissue: general environmental exposure (food, water, air), direct contact with synthetic materials worn close to the body, and the way immune cells can carry particles into tissue. Period products weren't singled out as the cause here — but they're squarely part of the "products in prolonged mucous contact" category that the researchers flagged as sensible to scrutinise first, simply because of how they're used.
This is exactly why Fri Period exists in the first place. We built our underwear from OEKO-TEX certified organic cotton and bamboo, made without PFAS, because we believe you shouldn't have to guess what's touching your body during your period. This study doesn't prove our underwear "solves" microplastic exposure — no one product can claim that, and we're not going to pretend otherwise. But it's a real, science-backed reason to think about material choices as one lever among several, alongside things like filtering drinking water and reducing synthetic fabrics generally.
Where the research goes from here
The open questions are genuinely open:
- Does more microplastic in reproductive tissue correlate with any measurable health outcome? No data yet.
- Are period products a meaningful source, or just one of many? Unknown.
- Do different polymers carry different levels of risk? Almost certainly — but that hasn't been mapped out.
Two larger studies are reportedly already underway, so this is a research area to keep watching over the next couple of years rather than a settled verdict.
The takeaway
You don't need to overhaul your entire routine overnight. But if you're already someone who reads ingredient lists and thinks about what's next to your skin, this is a good nudge to extend that same thinking to your period products — checking materials, looking for third-party certifications, and choosing fabrics you can actually name.
Knowledge is power, and a little curiosity about what you're wearing each cycle is never a bad thing.
Source: Sharma et al., "Human reproductive exposure to microplastics: a multi-technique analytical study of menstrual and amniotic fluids," NanoImpact, 2026.
