What can period blood reveal about a person’s health?

When you think of getting tested for a disease, you might think first of nasal swabs, urine tests, blood draws. Even though around 1.8 billion people across the world menstruate, period blood doesn’t come to mind.But that might soon change. Earlier this year, the U.S. Food and Drug Administration for the first time approved a health test based on period blood. The at-home test, which detects a biomarker for diabetes, offers an alternative to the blood draws typically required to diagnose the disease. It’s also a first step in a long-term vision for researcher Sara Naseri, CEO and cofounder of Qvin, the San Francisco Bay Area–based company that makes the test.“Women bleed every month, so why let that go to waste?” Naseri remembers wondering a decade ago as a medical student. Period blood, she thought, could be a convenient way to get clues to a person’s health — no needles required. When she couldn’t find much research on the approach, she decided to look into it herself.Then at Stanfor...