One of the first things you’ll want to know on learning you are pregnant is when the baby is due. When will the big day be?
To estimate your due date, count 280 days, or 40 complete weeks, from the first day of your last period. The expected due date is therefore only an approximate date.
An ultrasound (see Ultrasound) performed before 20 weeks of pregnancy will give you a good idea of the due date, plus or minus 7 to 10 days.
Ultrasound : An examination using an ultrasound device that can see the embryo or fetus in the mother’s womb.