Hi Gurnz and big congratulations on your pregnancy.
As some of the others have said there are varying reasons for using ultrasound in early pregnancy. For my four live children I only ever had the nuchal ultrasound at 12.5 weeks. However, when women have experienced frequent pregnancy loss especially if those babies haven't miscarried (a missed miscarriage) ultrasound is done to identify that there is a viable pregnancy. Any bleeding in pregnancy is usually checked with ultrasound to confirm that the little one is still growing and a heartbeat can be sighted. Also women who have been on fertility treatment generally have an early ultrasound to ascertain if there is a singleton pregnancy and the viablility of the pregnancy. Also for women who are unsure of when their LNMP was or where there is some question over dates an early scan can be useful to ascertain dates. Early scans are the most accurate at dating pregnancy - embryos grow at almost the same rate for each embryo. This growth can be nailed down to merely hours. So, you can see that could be helpful if that information would help contribute in a positive way to a pregnancy.

For women who have no history of these problems then an early ultrasound isn't necessary nor advised.

As with all things medical ultrasound can get overused. Also sometimes it takes away from the intuition and knowing that a woman develops througout pregnancy. The connection with her baby. Ultrasound is a wonderful tool, I for one am very thankful for it. However as I said in a routine pregnancy with no history, and no other indicators early ultrasound probably is unnecessary.