What menstrual blood is teaching modern medicine

I'll be honest about why this caught my attention. I've lived with type 1 diabetes for 23 years, so I've given more blood samples than I can count — fingertips, veins, the lot. The idea that some of that testing could one day happen from a sample I already produce every month, with no needle at all, is genuinely exciting to me. But hope and hype sit close together in women's health, so I've tried to separate what is actually approved and published from what is still a promise.

It helps to know that menstrual blood is not simply blood. Collected in the first day or so of a period, it carries shed cells from the endometrium — the lining of the uterus — along with immune cells, stem cells and, by one count, more than 350 proteins not found in ordinary circulating blood. That mix is exactly why it is useful in three very different ways: as a non-invasive diagnostic sample, as a renewable source of stem cells, and as a window onto the immune system.

A diabetes test that reads a pad, not a needle

The clearest real-world example arrived in January 2024, when a company called Qvin received FDA clearance for the Q-Pad — the first test authorised to measure HbA1c from menstrual blood. It looks like an ordinary pad, but it holds a small collection strip; you wear it, remove the strip and post it to a lab, which reads your average blood sugar over the previous three months. No finger-prick, no blood draw.

For anyone living with diabetes, HbA1c is the number that shapes every appointment, and I've watched mine be taken by needle for two decades. In Qvin's validation work, the pad-collected results tracked venous blood closely — correlation coefficients as high as 0.96 and a mean bias under 1%. The clearance is narrow for now (A1c only), but the company is researching the same approach for anaemia, thyroid health, fertility, endometriosis and perimenopause — conditions where women are often under-tested precisely because testing is inconvenient.

A renewable source of stem cells

The second use is more experimental but, to me, more astonishing. In 2007, scientists showed that the endometrial cells shed in menstrual blood include mesenchymal stem cells — now usually called menstrual blood-derived stem cells, or MenSCs. Unlike bone-marrow stem cells, which need a painful, invasive extraction, these can be collected non-invasively, month after month, from something the body discards anyway. They multiply quickly in the lab and provoke relatively little immune reaction.

In animal and early laboratory studies, MenSCs have been tested against a long list of conditions — liver disease, heart damage, stroke, wounds that won't heal — and, close to my own heart, type 1 diabetes. In one 2022 study, transplanting these cells into diabetic mice improved their symptoms and protected their organs, performing on par with the umbilical-cord stem cells researchers already use. It is important to be clear: this is mouse work, not an approved treatment, and the road from a promising rodent study to a therapy for people is long and littered with failures. But the source itself — accessible, renewable, ethically uncomplicated — is what keeps this field moving.

The autoimmune connection — what the research actually shows

You asked specifically about autoimmune disease, and it is a good instinct, because this is where menstrual blood gets most interesting. Start with a stark fact: roughly 80% of people with autoimmune conditions are women ↗, who carry up to four times the risk men do. The reasons are still being untangled — sex hormones, and increasingly the X chromosome itself — but the upshot is that autoimmunity is, disproportionately, a women's health problem. And menstrual blood is a sample only women produce, packed with the very immune cells involved.

Two threads are worth watching. The first is that MenSCs don't just regenerate tissue — they calm the immune system, dampening overactive T cells and B cells. In a mouse model of multiple sclerosis (experimental autoimmune encephalomyelitis), menstrual blood-derived cells eased the disease specifically by inhibiting T-cell activation. That same immune-modulating property is why mesenchymal stem cells more broadly are being trialled in lupus, rheumatoid arthritis and type 1 diabetes — all conditions where the immune system attacks the body's own tissue.

The second thread is diagnostic, and it runs through endometriosis — a disease that affects roughly one in ten women, takes seven to ten years to diagnose, and shares many features with autoimmune conditions, including the broad T- and B-cell activation doctors use to define autoimmunity. At the Feinstein Institutes in New York, the long-running ROSE study (Research OutSmarts Endometriosis), led by Christine Metz and the autoimmunity geneticist Peter Gregersen, is analysing menstrual effluent cell by cell, using single-cell RNA sequencing, to build a non-invasive test that could replace diagnostic surgery. Related work now uses the immune profile of the endometrium to assess women with systemic autoimmune diseases such as lupus before they try to conceive ↗.

None of this means menstrual blood is a magic key to autoimmune disease. But it gives researchers something they have rarely had: repeated, low-cost, non-invasive access to immune cells from the exact population most affected.

The honest caveats

Because this is women's health, and because I've been burned by overselling before, here is the sober version. Only one menstrual-blood test is FDA-cleared, and only for HbA1c; the endometriosis tests are still in research, not on pharmacy shelves. The stem-cell therapies are overwhelmingly preclinical — cells in dishes and studies in mice, not proven treatments you can ask for. Be wary of any clinic already selling menstrual stem cell cures; the science isn't there yet. What is real is the direction of travel, and it is genuinely promising.

Why a discarded sample matters so much

The thread running through this whole journal is that women's health after 40 — and women's health generally — has been under-studied for a long time. Part of the reason is practical: research needs samples, and samples usually mean needles, clinics and cost. Menstrual blood quietly removes that barrier. A sample most of us have spent our lives throwing away turns out to be a monthly, needle-free readout of metabolism, hormones and immunity. If even a fraction of this research delivers, the humble period could become one of the most useful diagnostic tools we have — and, for once, one built entirely around the female body.

What the research says

This is a fast-moving field, so here is where the evidence stands today — what is approved, what is published, and what is still confined to the lab.

I'll keep an eye on this as the trials and tests mature. For now, the take-home is simple: the next time you're told there is not enough research on women's bodies, know that some scientists have found their answer in the one sample medicine spent centuries ignoring.