Which country?
My friend also had this experience. Instead of being given progesterone, which is what's given here in the US, she was given HGC in her native country of France.
Theoretically, once in the body, progesterone and HCG at that early conceptual stage have similar roles, in that HCG stimulates the corpus luteum to produce progesterone, and progesterone prepares the endometrium to receive the fertilized egg. But it's interesting that some women react differently to each molecule. More research is needed.
Anyway. Congratulations!