Chances of having a normal pregnancy after mc?

We have 2 boys already and both were great, uncomplicated, full term pregnancies. Well 5 days ago I had a mc. I didn't smoke, drink, or use drugs and I didn't have a bad infection (I did have a cold when I was about 5 weeks before I even knew I was preggo) and there is no fertility problems for us and I have no medical problems. I am also almost 24 so I am at a great child bearing age. There is also family history of birth defects, down's syndrome, etc. The doctors are uming that it was just an abnormality with the pregnancy like most are and it naturally rid itself. Well anyway to get to my question, what are the chances that I will have a mc again? What are my chances of having a healthy pregnancy next time? I have heard mixed stories. I have heard that your chances of having a normal pregnancy go down each time you have a mc. I have heard that if you only have one and have had a normal pregnancy before, that it doesn't increase your chances of having another one. So what is true?