More like 30%. Fewer still track their periods, and the details of how they are timed, as well as entry into or exit from the pool of people who do, can be an i

More like 30%. Fewer still track their periods, and the details of how they are timed, as well as entry into or exit from the pool of people who do, can be an indicator of much more sensitive information than the simple fact of being a woman who falls in a certain age range. The fact of the matter is, this data isn't just comparable to medical history; it is medical history.