Note the first day of your last menstrual period (LMP). Count forward 9 months from the date. Add 7 days to the date (& 1 year if the months enter the next year).
That’s it. See examples below;
Many pregnant women often get confused about their due date or expected date of delivery. If your cycle is normal 28 days, this is around 40 completed weeks of pregnancy or 9 months or 280 days from the first day you saw blood in your last menstrual period (LMP).
If your cycle is longer than 28 days, add the difference between your cycle length & 28 days to your calculated date to compensate. If it’s shorter than 28 days, subtract the difference from your calculated date to compensate.
Step 1: Let’s say your LMP was 12 June, 2020
Step 2: Count 9 calendar months forward from June (which is March, next year!)
Step 3: Add 7 days which is 12+7=19. Since it enters another year, add 1 to 2020=2021. So your EDD is 19 MARCH, 2021.
If you have a longer cycle say 35days, you need to add 7days to your Calculated EDD, i.e. 19+7=26. So it’s 26TH MARCH, 2021.
Similarly, If you have a shorter cycle say 21days, subtract 7days from your Calculated Due date, i.e. 19-7=12. So it’s 12TH MARCH, 2021.
If your 9 months don’t cross into the next year, you won’t need to add 1 year to your LMP year. For e.g. if your LMP is in January, your EDD will be in October of same year & you won’t add 1 year. But if LMP is June, EDD will be March of the next year, so you will add 1 year.
Note that you can deliver once your pregnancy is “term” i.e. anywhere from 37 to 42 weeks. Most women deliver within this range of time. But people still calculate EDD because most women want a specific date, not a range of time.