During your pregnancy, everybody will ask you when your baby is due. This is also one of the first questions that future parents ask themselves when they see the "magic plus sign" on the home pregnancy test. You don't have to wait for your first doctor's appointment to find out your due date: you can calculate it yourself.
Pregnancy generally lasts 280 days, counted from the first day of your last period before pregnancy. If you can remember this date you can use the calendar to count 280 days. The easiest method is to add seven days to the date of the first day of your last period and then deduct three months.
Useful tip: when people ask you when you are due, only give the real date to those who are closest to you. For everyone else it is better to add a week. First babies are often slightly late, and there is nothing more annoying than your neighbour coming up to you in the shop every morning and asking "what are you waiting for?"