Calculate Your Due Date
The following information which contains three steps to determine your due date is based on Naegele's Rule. Naegele's Rule is based on a normal 28 day menstrual cycle.
To get started you must realize that a pregnancy lasts 280 days or 40 weeks. The first day of the last menstrual period is considered day one.
To determine your estimated due date (EDD), follow these three easy steps.
- Determine the first day of your last menstrual period
- Count back three calendar months from that date
- Add one year and seven days to that date = Estimated Due Date
Because some woman may have longer or shorter menstrual cycles, the Estimated Due Date may have to be adjusted. Be aware that less than 10 percent of woman actually give birth on their calculated due date. Delivery two weeks before or after the estimated due date is still considered normal.