Pregnancy calendar: A pregnancy calendar is a chronological depiction of changes in a pregnant woman and the embryo/fetus during the 40-week course of pregnancy. Pregnancy calendars usually describe development and growth of the fetus and changes in the mother's body at weekly intervals. The calendar is calculated based upon the date of the woman's last menstrual period (LMP) and include the predicted date of birth (due date), sometimes referred to as the EDC, or estimated date of confinement.