I found these links by typing "low HCG" into Google. Basically, it looks like that if your HCG levels aren't doubling every 48 hours or so, that is cause for concern that you might have a blighted ovum or an ectopic pregancy or something else. However, it is possible to have a normal pregnancy with slow HCG growth.http://www.medhelp.org/forums/matern...hive/3103.htmlhttp://www.parentsplace.com/expert/o...112720,00.htmlhttp://forums.obgyn.net/pregnancy-bi...9809/0153.html
How much do you know? Do you know the actual HCG levels recorded, and how many days apart? Were the levels actually dropping, or just not growing as quickly as they want?
I hope that everything goes well for you.