The Cycle Book: An Interactive Step-by-Step Guide to Tracking Hormones and Knowing Your Body

Millions of people track their cycles on apps because it's a convenient way to know when your next period is likely coming. But those apps are also tracking your data, sometimes in ways that are not legal or consensual. And they don't go deep enough. What's worse, they're also leaving users vulnerable to surprisingly inaccurate fertility predictions, with some studies estimating efficacy at about twenty percent for correctly predicting ovulation.



Written by a midwife and a clinical sex thera...