Have you done any blood work on this pregnancy?
I am so sorry for your losses. I had 4 m/c last year, and I understand your fear. I have just finished a whole bunch of tests and was given the thumbs up today to start ttc again...with no answers as to why. And I am 40. Many OB"s won't do testing until after your third miscarriage. However, if one of your losses was due to trisomy 16, you have your answer, and it doesn't sound like you need a whole lot more info. Chances are good it was just bad luck. If you have 2 healthy children, that tells you a lot as well. I know its scary, and you should talk to your OB about it. In my case, my OB has promised me early ultrasounds and regular bloodwork to ensure my HCG levels are rising. There is nothing that can be done to stop a first trimester miscarriage, but the constant reassurance will be helpful to me. Perhaps you may want to ask the same? Other than that, all you can really do is see the genetic counsellor.
It's natural to be afraid after 2 losses. I can tell you there are many many women on this forum who have been through 2 or more m/c and gone on to have healthy pregnancies and babies...you can too!!!! Good luck to you!