The estimated date of delivery is the date on which you are most likely to deliver your baby. It is commonly known as the pregnancy due date. The measurement of how many weeks far along you are in your pregnancy in weeks is called the gestational period. It is important for both you and your obstetrician to know your gestational age as it helps in providing the right care for mother and foetus at every stage of your pregnancy. However, due date is only an estimation of when you will give birth and it does not mean that your baby will be born exactly on that date. Considering that usually a pregnancy can last anywhere between 37 and 42 weeks, and that the date of delivery depends on a variety of factors, your baby may be born a few days earlier or later than the estimated due date.