Most pregnancies last around 40 weeks (or 38 weeks from conception), so the best way to estimate your pregnancy due date is to count 40 weeks from the start of your last period. This is how your doctor will estimate your due date – and it’s a pretty solid target. But remember: It’s just as normal to deliver a week or two before or after.
Unfortunately, no one can say for sure exactly when your baby will arrive. In fact, only about four per cent of babies are born on their due date! But it is likely that your baby will arrive in the few weeks either side of your estimated due date. Knowing this can help you to be prepared for labour and birth, and to have everything ready for your new baby.
It may do. Your first pregnancy scan will probably happen when you're between 10 weeks and 14 weeks pregnant. It's known as the dating scan, and is used to give you a more accurate due date, based on the size and development of your baby.