I am 39 and had 3 m/c's all before 12 weeks. The last m/c the baby had Turner Syndrome. I am now 21 weeks along and doing well with this pregnancy. With this pregnancy they did an u/s at 6 weeks and 11 weeks...but they even said that there's nothing they could do if there was something wrong...but it did give us peace of mind. They also had me on folic acid and prenatal vitamins before I was even pregnant. Just keep the faith and it'll work out fine.
I know I was watched more closely after all of my miscarriages - with each pregnancy. But to be honest if it's going to miscarry there isn't much they can do about it. Sometimes taking baby aspirin helps but they generally thel you to do that if there is some underlying medical condition.
After my first couple of miscarriages they did lab work for multiple miscarriages, but since you are already pregnant that doesn't make a lot of sense.
Good news you already have two children, so there's probably nothing wrong with your uterus, or general genetics, and what not. You just got unlucky and had two bad eggs.
Tell your OB you've had multiple miscarriages and usually they respond to this. But all they really do is monitor your hcg levels to make sure they are doubling, then you go in a couple of times for early ultrasounds...and sometimes the baby aspirin and/or heparin, or progesterone. But if it is a bad egg with chromosomal problems those don't really do anything to help the pregnancy. Miscarriages are pretty frequent. Althouh you are aren't that old for multiple chromosomal miscarriages (probs you'd have if you're 40).
So talk to you doc and they should watch you a little more closely...I know miscarriages suck, but many of us have had them and we do keep trying. Lucille Ball had something like 9 miscarriages. So it's just a persnoal decision you have to make as to whether or not you want to continue trying. Good luck to you. You will probably be lucky this time...3rd times a charm! You're baby factory is still in good condition and not quite ready to shut down yet. I bet this pregnancy will work out just fine. Go to anothe OB if you don't think this one does the job.