Unless things have changed in the last two years, here in the UK it is normal to have two scans: a Dating Scan (booked for 12 weeks as determined by the likely last menstrual date) and a Diagnostic Scan (booked for around 20 weeks as determined by the 12 week scan). I was only offered the Dating Scan 4 years earlier with DD1 as I had an uncomplicated pregnancy, but by 2006 everyone was being offered the Diagnostic Scan too, although they were surprised we had come as I turned down the invasive tests eg Amiocentesis, but I just couldnt resist seeing DD2 for the third time. She was also scanned at 6 weeks due to a previous miscarriage. Other reasons for Ultrasounds can include a baby not growing within the expected parameters, a low lying placenta, and other general concerns. One of my friends seemed to have her DS2 scanned every other week, in part coz her first pregnancy was a disaster, and in part because the chord only had two blood vessels not 3. As she said herself, if she hadnt had so many scans she would have been a lot less stressed. But all in all, most people opt to have the couple of scans offered. It's the most you're going to see of them in the first 9 months!

I have sofar this pregnancy (I am 16 weeks), had 2 ultrasounds, one at 7 weeks to establish a due date, and one at 12 weeks for other reasons, getting the early ultrasound is more than normal practice here in Australia as i had the dating ultrasound for my last pregnancy too.

My sister had to have a dating ultrasound. To be acurate it has to be before 12 weeks. The 12 week ultrasound is to check for things like Downs Syndrome. Sometimes they change your estimated due date at the 12 week scan and the 18 week scan but my Sonographer (ultrasound person) told me the date is not acurate unless it is done before 12 weeks. (not that they really have any idea when the baby is going to actually come out, unless it's a plan C-section)

i think you will find they go by the measurements to work out the due date on a ultrasound

If you are uncertain of the date of your last period or your doctor wants to do one to make sure that the dates are accurate, then an ultrasound will be needed in order to establish a due date of your baby or to confirm a suspected due date.

All ultrasounds check the size of a baby at several stages of gestation as well as to make sure that everything is ok.

Ultrasounds are usually a non-invasive procedure and can be a very emotionally overwhelming experience as you get to see your unborn baby growing and moving around.  You will be able to see and hear the heartbeat, see the bits and pieces of your baby and if around the 20 weeks mark, might even be able to find out the sex of your little one.

I've had 5 babies now, and with each one, have had at least 2 ultrasounds.  My first, I had 4 ultrasounds done over a 21 week period, but I had to have them done due to previous history and the fact that I got very sick.  I'll never forget being able to see the heartbeat and watch my little one move and groove away.

The ultrasound clinic will give you the info you need about what you need to do before an ultrasound.  Most times, your partner will be able to be there with you to share the experience.

My advice is to enjoy the experience.  Watch your baby moving about and know that you are part of something special, part of the miracle of creating life. 

Yes, like Izzy said the first one around 12 wks is for this.

I had a dating ultrasound with my first daughter because I wasn't sure when my last period was before I fell so they could give an acurate due date.

My SIL also had a dating ultrasound because she was in denial for three months that she was pregnant and so didn't know how far she was, it was at this ultrasound that they found out it was twins.

Yes. The first ultrasound is usually to check how things are and they also date the baby. I

My first ultraound with both my pregnancies is to check that everything is alright, check to see the heartbeat and among other things, to see that I am as far along as the doctor suspected.