In my program, I will investigate the origin of the so-called “cartouche” surrounding each of the 20 named day glyphs and how it provides evidence for the gestational hypothesis that the 260-day cycle was invented by midwives to calculate a child’s birthday. Several ethnographers have documented the work of Maya midwives, spanning many years, many languages, and many communities. In particular, many Maya K'iche' midwives have consistently told ethnographers that they use the 260-day cycle by noting the day of the first missed menstruation and then counting 260 days forward to predict the birth of the child. If women keep a record of the days on which their menstruations occur, they will note the date of the expected and missed menstruation. If each day is understood to be a day of potential blood, then it becomes clear why blood would be used to describe each day.