I had low progesterone levels with this pregnancy (I'm 18 weeks). I had to take Prometrium, a progesterone suppliment. It was a pill that I took once a day. I had to take it until I was 13 weeks. I know they also have one you "take" vaginally, shots and different pills you take more then once a day.
When I was pregnant my levels wouldn't rise so they gave me progesterone/oil for the first three months, which means-- i got shots every other day for three months, which means, my husband learned to give me shots in my ass every three months, which means--we got MADELINE!!!!