How Your Pregnancy Due Date is Calculated
It's the most common method between healthcare providers
16 July 2017
Once you have confirmed you are pregnant, it is probably a good idea to calculate a due date so you can plan ahead.
The average pregnancy term is calculated as 40 weeks from the first day of your last menstrual period. However, only 1 in 20 women give birth on their actual due date and most pregnancies range between 37 - 42 weeks. A baby born at 37 weeks is considered premature and a baby born at 42 weeks is considered overdue. Yeah, babies don't stick to a timetable, but it still helps to know your due date so that you can plan ahead.
And while there are many pregnancy due date calculators available online (we have one too), it is important to understand how the dates are worked out.
In order to calculate your baby’s due date, add seven days to the date of your last period and then add nine months (280 days). For instance, if your period ended on Jan 1, adding 7 days would make it Jan 8 and then adding 9 months would make Oct 8 your due date.
This is, of course, only an estimate. Once you are more than six weeks pregnant, you can get ultrasounds done to check the development of your baby and estimate a more accurate due date based on her development at that stage.