How is your due date calculated?
Your due date is also referred to as your EDD (estimated date delivery) or EDC (estimated date confinement).
Your pregnancy is calculated from the first day of your last menstrual period rather than the date of conception. As women can vary in the length of their menstrual cycle, this can affect the due date. For example, a woman with a 35 days cycle will be due approximately 7 days later than a woman with a 28 day cycle.