low progesterone?

Anyone have low progesterone levels? I took my first positive test last week and had blood work done Wednesday; my levels then were Progesterone 14.8 and HCG 33.6.  I had blood work done again yesterday and my levels were Progesterone 8.7 and HCG 1,311.  My Dr is starting me on Progesterone supplements and I'm just curious if anyone else has had this problem. I didn't with my first son and I just don't know what to think of this! Thanks for any help 😊❤👶🏻