mean progesterone concentrations ( +/- se ) in plasma from foaling to foal heat and during estrus , luteal phase and pregnancy were .51 +/- .09 ng/ml , .53 +/- .08 ng/ml , 3.88 +/- .26 ng/ml and 4.22 +/- .09 ng/ml , respectively ;
C0033308
progesterone
C0032961
pregnancy