Normal HCG with Low Progesterone: Understanding Early Pregnancy Concerns

Question
I was wondering if it is threatening if HCG levels are normal, but progesterone levels low?  I had a blighted ovum miscarriage in my first pregnancy (December 05) and my hcg level maxed ad 57.  I conceived 2 weeks later (next ovulation) and had a hcg/progesterone test done at 12dpo.  My HCG was 118 but my progesterone .3.  I had another HCG yesterday- 16 dpo and my HCG was 486. The didn't check progesterone in that one.  I have very sore breasts and I am very tired.  
So, should I be worried?  Or, if there was a problem, would HCG not be rising as it is?  Is progesterone really a factor in predicting viability of a pregnancy?
Thank you in advance for your time and for offering this website.
Wendi

Answer
Progesterone maintains the pregnancy until the placenta takes over at around 12 weeks gestation. A low level of progesterone can lead to miscarriage and has nothing to do with HCG values, which can continue to rise  in the presence of a low progesterone. If you have a low progesterone level, I would suggest that you start progesterone supplementation until 12 weeks gestation. HCG values should double every 48 hours in a viable pregnncy.