In general I think it's not standard practice to have hcg levels monitored with blood tests, but if you really want it done, then have a chat to your doctor because I'm sure most doctors would be happy to let you have it done if you are worried and it would reduce your anxiety levels.

EDIT: Just wanted to add... Remember though that hcg levels are not always indicative of a healthy or non-healthy pregnancy. I didn't have hcg levels monitored with my first pregnancy that ended in us losing our angel, but when I questioned my Ob about whether we would have know earlier if we had monitored hcg levels, he said no because all the right hormones in my case were being made. On the flip side, there have been a lot of ladies on this site that have had hcg levels that didn't look like they were rising the "right" amount that have gone on to have perfectly healthy bubs...