Can the level of HCG in blood tell me whether my pregnancy is a healthy one or not ?

Yes – but only to a certain extent.  The HCG ( human chorionic gonadotropin) hormone is a remarkable molecule which is very unusual because it is produced only by the cells that will become the placenta of the developing embryo (trophoblast cells). Once the embryo implants in the uterine lining, these cells start producing HCG . It takes a few days for the HCG hormone to build up in the body to a level, which is high enough for it be detected in the blood or urine of pregnant women. Normally, you do your first pregnancy test (HCG blood test) 14 days after embryo transfer.  At this point, if the embryo has implanted, you will also get a positive urine pregnancy test. The HCG hormone level in the blood doubles every 48-72 h. If the HCG level doubles well, this indicates that the cells of the embryo are dividing well , suggesting that the pregnancy is progressing normally and is healthy.  This is why monitoring the HCG blood levels during the first few weeks  helps to make sure that the pregnancy is advancing as expected. A drop in HCG level during this time is a sign that the pregnancy is not healthy.  Make sure that you measure your HCG level in the same lab each time to avoid discrepancy in the results.

However, do remember that because the HCG is produced by the trophoblastic cells of the embryo, just because the level is rising well does not always mean that the pregnancy is healthy. Thus, while a drop in HCG confirms the pregnancy is doomed, a rising HCG level provides limited information. 

Also, once the HCG level crosses 1000 mIU/ml, a vaginal ultrasound scan provides much more useful information than just the HCG levels,  because it allows us to actually visualize the development of the growing embryo. 

Read more at : http://www.drmalpani.com/hcg.htm