Sometimes a single question can open up a whole new world. About ten years ago, a young doctor named Sara Naseri was trying to think of how the field of medicine could be more preventative. It was so difficult to get information about what was going on inside people’s bodies, before they were sick enough to go to a doctor for a blood draw. Suddenly it dawned on her: Women bleed every month. What can we learn from that blood, and why has no one looked at it before? A rigorous scientific study followed—and eventually, a Silicon Valley start-up called Qvin, which produces menstrual pads used for testing women’s blood. Dr. Naseri represents a new generation of women coming up with innovations to close the women’s health gap. We travel to Silicon Valley to meet her, and we talk to two venture capitalists about the impact women in venture are having on private sector efforts to improve women’s health.