I didn't have any blood tests etc until I had the one for my 12 week NT scan. They checked a few different things then. I did actually ask about why they didn't do bloods to measure HCG levels early on and my OB said that he doesn't think it's wise because there is nothing you can do about the results. In his opinion it can cause unnecessary worry and if you are going to miscarry, you will regardless of whether or not you have blood tests. But if it your HCG levels just take a little while to get there, the unnecessary stress doesn't help you or the baby.

So I wouldn't worry about tests etc, just enjoy being pregnant!