We’ve Been Measuring Our Periods Wrong Since 1980

Your period product’s absorbency rating was never tested with blood. It was tested with saline (water, salt, bicarbonate) since the 1980s. And despite what 2023 headlines implied, that hasn’t changed. Manufacturers still use saline today.

What did happen in 2023: OHSU researchers ran the first-ever study testing real absorbency with donated blood. Period underwear (marketed for heavy flow) held the least ~1–2 mL. Menstrual discs held the most at 61 mL on average. Tampons, pads, and cups fell so