HCG levels rise, then drop, then rise again after IVF

LMP 05/01/09
Egg retrieval 05/14/09
Transfer 3 days later
HCG level 12 days post retrieval 65
HCG level 15 days post retrieval 94
HCG level 18 days post retrieval 82 -went off progest. and estrog.
HCG level 20 days post retrieval 91
HCG level 22 days post retrieval 187
HCG level 25 days post retrieval 486 went back on progest. and estrog.

Two embryos were transferred.  My RE is not sure what is going on.  I am scheduled for an ultrasound on 06/11/09, which is one day short of 6 weeks since LMP.  After receiving the news that my levels had dropped from 94 to 82, my RE told me that I was miscarrying and to stop all meds.  Now, since my levels have started doubling they have put me back on my meds (estrogen and progesterone, which by the way, were at very high levels when I stopped taking them so I know my hormone levels are not causing a problem).  Everything I have read says that when hcg levels drop you are miscarrying but I have had no spotting and now my hcg levels are going up again.  I wondered if maybe both embryos implanted, one earlier than the other, and the first one did not survive, causing the drop in hcg levels.  That might explain why I still have increasing hcg levels now (the second embryo that implanted is now developing normally).  My doc also said we have to watch for an ectopic pregnancy.  I am just really confused right now and can't find any information on the internet about hcg levels that initially rose, then dropped, then rose again.  Any help would really be appreciated!

[Elaine Brown, MD]

Hi!
I think that you have hit the nail on the head with your two theories.  I also wonder about the possibility of twins with one starting to grow and produce HCG, and then stopping, while the second one continued.  Don't forget the possibility of identicals too, which happens more often after IVF than we see in nature.  Ectopic is certainly not ruled out either.  You are going to have to wait for the ultrasound for the final analysis.  How Nerve-wracking!  The levels look asbsolutely beautiful if you ignore the first three!  If it were a natural pregnancy, the progesterone level would be useful, but yours is artificially sky high, so not of use.  I hope it turns out well--I just have a feeling that there's a viable one in there!  Good luck!
Dr B