Although a woman will get her period about 450 to 480 over the course of her lifetime, most women know surprisingly little about their cycles. For women who take oral contraceptives, their menstrual cycle takes on an entirely different dimension: they need to count days (they only need to glance at their dispenser to see how many days are left in any given cycle). With the recent popularity of long-term contraceptives, some health experts are questioning whether women even need to bleed every month. Why not quarterly? Or once a year? What about, never? It’s no wonder that the menstrual cycle is a mystery to so many.