plasma concentrations of progesterone and 17 alpha-hydroxyprogesterone were high in the 2nd and 3rd months of gestation , but 20 alpha-dihydroprogesterone increased from a level of 2 ng/ml , during the first 3 months , to 10-15 ng/ml during months 5-10 , to reach 80-120 ng/ml during the last 30 days before foaling .
C0033308
progesterone
C0012311
20 alpha-dihydroprogesterone