There are various reasons why your due date may be incorrect. For example, if you have an irregular cycle or are unsure when conception occurred, your due date may be out by a few days or more. Even if you had a dating scan, it is still possible that your confirmed due date could be inaccurate.
Another thing to remember is that your due date is just an estimation, and is based on the average length of pregnancies. In fact, there is not a one-length-fits-all gestation period; some pregnancies are slightly longer or shorter than others.
If you are wondering what to do with your very-pregnant self, take a look at these suggestions: