Menstruation is something half the world does for a week at a time, for months and years on end, yet it remains largely misunderstood. Scientists once thought of an individual’s period as useless, and some doctors still believe it’s unsafe for a menstruating person to swim in the ocean wearing a tampon. counters the false theories that have long defined the study of the uterus, exposing the eugenic history of gynecology while providing an intersectional feminist perspective on menstruation science. Blending interviews and personal experience with engaging stories from her own pioneering research, Kate Clancy challenges a host of myths and false assumptions. There is no such a thing as a “normal” menstrual cycle. In fact, menstrual cycles are incredibly variable and highly responsive to environmental and psychological stressors. Clancy takes up a host of timely issues surrounding menstruation, from bodily autonomy, menstrual hygiene, and the COVID-19 vaccine to the ways racism, sexism, and medical betrayal warp public perceptions of menstruation and erase it from public life. Offering a revelatory new perspective on one of the most captivating biological processes in the human body, will change the way you think about the past, present, and future of periods.