Sometimes the most consequential innovations are fueled by frustration. When she was in her early thirties, Ridhi Tariyal asked her gynecologist for a fertility test. Her doctor dismissed the request, saying such a test wasn’t possible. Tariyal knew otherwise. With an MBA from Harvard and a Master of Science in biomedical enterprise from MIT, she was familiar with the Anti-Müllerian Hormone, an established marker of ovarian reserve. The test existed. Still, her doctor would not order it.

The experience left her frustrated enough to turn her own health into a science project. “There are thousands of women like me,” Tariyal, now 45, says. “Women are waiting longer to have children, but they still want information about their reproductive health.”

Regular fertility tests require blood samples, so that raised an obvious question: Where could women collect blood easily and repeatedly without a clinic visit?

The answer, she realized, was hiding in plain sight. Every month, billions of women discard biological material containing blood, immune cells, bacteria and fragments of tissue shed from the uterine lining. According to Taryal, over 800 genes are expressed differently in menstrual effluence and venous blood. Yet, she notes, “We throw all this valuable information into the trash.” What if menstrual blood could reveal fertility, detect disease and provide a window into women’s health, all without invasive procedures?