Understanding hCG Levels in Early Pregnancy: A Doctor's Explanation

Question
Dr. Rappaport:  I am 36 years old, I have 2 biological children (4 adopted) and my LMP was 8/29, but I have a longer cycle.  I ovulated on 9/16.  I had 3 positive pregnancy tests and an u/s on 10/11 giving me a 6/11/06 due date.  The u/s was confirming the pregancy but they wanted to get hCG levels to make sure.  My levels reached 3600 on 10/14 but my last level on 10/20 went down to 2900.  My pcp told me that this pregnancy is probably not viable.  My question is this:  I am not experiencing any cramping or bleeding/spotting.  Do these levels ever go down and a healthy baby delivered, or am I just hoping where there isn't any hope left.  I've had 2 previous m/c (1st at 11 wks, 2nd at 8 weeks).  What could be the cause of this one if in fact I am m/c?  Thank you for your time

Answer
It is certainly not a good sign when HCG values drop. However, if a sonogram shoed a viable pregnancy and you had values of 3600, I would repeat the test in a week or repeat the sonogram. Since you are over 7 weeks gestation, you should see a fetus and a fetal heartbeat, which is a good sign.