Your midwife may recommend an early scan at between six weeks and 10 weeks if you have experienced bleeding, pain, or problems in a previous pregnancy.

The whole point of the scan is to work out how many weeks pregnant you are.

You may have calculated the length of your pregnancy from the first day of your last menstrual period (LMP).

However, conception doesn't actually occur until around 14 days after your LMP, or later if your cycle is longer than 28 days.

You may know when your LMP was, but not when you actually conceived.

Having a scan in the first few months of pregnancy can be a thrilling experience.

It's amazing to see the little blob with a heartbeat that will soon become your baby.For most mums-to-be, the first scan will be a dating scan at between 11 weeks and 13 weeks plus six days of pregnancy.However, the timing of your first scan will also depend on how your pregnancy is going, and where you live.If you do know the conception date, this is counted as day 14, not day one.If your cycle is irregular or you've recently been taking the contraceptive pill, working out the date from your LMP probably won't work. If the scan date differs from your period dates, the scan date will be used.The scan will usually show that your pregnancy is less far along than suggested by your LMP.