It's quite individual with booking in and scans etc. If you are not a High Risk pregnancy, then generally once you have seen your doctor to confirm your pregnancy they will send you for a dating scan - this is when you find out how many weeks you are. There is a 12 week Nuchal Test if you want a SCREEN test for Down Syndrome. 18-20 week scan that checks for abnormalities, then again at 36 weeks to check positioning before labour.
In that course should the Doctor/Midwife/OB need to monitor something they will let you know and you may have more tests/scans more often. I have a scan each time I attend the Clinic, I am in a Public Hospital, they wanted to monitor something found early in pregnancy, which has been fine ever since, but once they THINK something might not be right they watch you throughout the whole pregnancy, as it is neglegant not to do so. Even if the chances are very very low of something being wrong.
Hope this helps.. Goodluck smile