in order to study the changes of c21-steroid levels which included pregnenolone ( p5 ) , 20 alpha dihydropregnenolone ( 20p5 ) , 16 alpha hydroxypregnenolone ( 16p5 ) , progesterone ( p4 ) and 20 alpha dihydroprogesterone ( 20p4 ) in maternal peripheral blood during pregnancy and at delivery , these steroids were measured by gc-mass with application of deuterated steroids as internal standard .
C0033006
c21-steroid
C0038317
steroids