The long – and strange – history of testing menstrual blood for health conditions

There’s good news for anyone who menstruates and doesn’t like the needles involved in blood testing. In January 2024, the biotechnology research company Qvin won FDA approval for their Q-Pad product – a menstrual pad with a removable strip to collect blood samples for clinical tests. It offers a needle-free way of testing menstrual blood for signs of diabetes.

This may only be the beginning of tapping into the huge potential of using menstrual blood in this way. Blood testing, as we know it today, began in the 19th century. But using menstrual blood in diagnosis has a longer history than many people realise.

Part of that involves a shift away from seeing this blood as a waste product. Before ovulation was discovered in the early 20th century, regular monthly bleeding was seen as essential to women’s health. It was thought to be the only way they could get rid of “excess” blood, which was supposedly produced from the normal processes of eating and drinking.

Following the theories of the influential ancient doctor Galen, people believed that the liver made food into blood. Because women’s flesh was supposed to be more “spongy” than men’s flesh, it was thought that it sent any blood that wasn’t needed by the body for its nourishment downwards, hence menstruation.

In the medieval book De Secretis Mulierum (On Women’s Secrets), the womb was described as “like a sewer situated in the middle of the town where all the waste materials run together and are sent forth”. There’s a 2,000-year history of this view, with the womb thought to not only get rid of spare blood but also to use that blood to flush out any bad substances from the body.

There were more positive ways of framing this. Having access to a sewer was thought to be a lot better for the body than not having one. So, in a belief system where it was all about waste products, that extra way out of the body could even give women a health advantage. One Hippocratic writer noted that, in some fevers: “Though many women fell ill, they were fewer than the men and less frequently died.”

Some western Europe medical writers went further still. They saw the womb as the most miraculous of all body parts, and praised its efficiency not just in processing waste but also in forming, holding and nurturing a baby.

But alongside this view, 16th-century medical writers came up with others. Some didn’t see menstrual blood as in any way “bad”, but just like all other blood. After all, they also believed that babies were made out of their mothers’ blood, and that breast milk was made of menstrual blood – so it couldn’t be entirely bad. Others saw it as not quite the same as other blood, but still “useful excrement”.

Western European cultures held various taboos about the power of menstruation to stop jam setting, or to prevent bread from rising. But alongside these beliefs, medicine was already using the appearance as well as the regularity of menstrual bleeding as evidence of various medical conditions.

In the 5th and 4th century BC, people thought about the body in terms of the various fluids it contained. Not just ones we’d recognise, like blood and phlegm, but also yellow bile and black bile.

Menstrual fluid was inspected for evidence that one of these fluids was present in too large a quantity. If the menses were shiny and black, and did not form clots, that was evidence of too much bile. White membranes “like cobwebs” meant there was too much phlegm. Both of those were considered a danger to women’s health.

The new ways of using blood involve putting a pad in your underwear and sending it off for analysis. In these ancient Greek medical texts, there is a test which works in very much the same way.

A woman is asked to menstruate on to a piece of folded cloth spread out over fine ashes. She should have a day cloth and a night cloth. When the cloths are washed out, they should be dried in the sun and inspected. If the problem is phlegm, the rags will look like they have mucus on them. If it’s bile, they will look reddish.

So, we may not still keep menstruating people away from jam and baking bread but many of the ideas of past are echoed in today’s medical knowledge and “new” technologies.

Helen King does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.