Hi there, Lets see if i can explain this so that you all can understand how the medical professionals calculate an EDC.
A full term gestation is 40 weeks. Your EDC is determined using the first day of your LMP. So if you look on a calender and find the first day of your LMP and then count 40 weeks that will be your EDC.
In all actuality you really are only pregnant 38 weeks total, due to the fact that your EDC is calculated using your LMP and conception usually occurs at approx 15 days (mid/halfway) into your cycle. So the first two weeks counted of the 40 week gestation you arent usually pregnant as conception hasnt occured yet.
Hope this helped and didnt cause more confusion!